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Digitized by the Internet Archive 
in 2011 with funding from 
The Library of Congress 



http://www.archive.org/details/manualoffishcultOOunit 



U. S. COMMISSION OF FISH AND FISHERIES, 

JOHN J. BRICE, Commissioner. 



^L 



MANUAL OF FISH-CULTURE, 



BASED ON THE 



METHODS OF THE UNITED STATES COMMISSION 
OF FISH AND FISHERIES, 



CHAPTERS ON THE CULTIVATION OF OYSTERS AND FROGS. 



Extracted from TJ. S. Pish Commission Report for 1897. Pages 1 to 340, 
Plates 1 to 62 and I to XVIII. 



WASHINGTON": 

GOVERNMENT PRINTING OFFICE. 

1897. 



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7 



A MANUAL OF FISH-CULTURE, 



BASED ON THE 



METHODS OF THE UNITED STATES COMMISSION OF FISH AND FISHERIES. 



PREPARED UNDER THE DIRECTION OE 

JOHN J. BRICE, 

UNITED STATES COMMISSIONER. OF FISH AND FISHERIES. 



TABLE OF CONTENTS. 



Introduction 5-6 

The Salmons of the Pacific Coast 7-26 

The Atlantic and Landlocked Salmons 27-70 

The Eainbow Trout 71-89 

The Brook Trout 91-101 

The Lake Trout 103-117 

The Whitefish 119-131 

The Shad 133-158 

The Black Basses, Crappies, and Eock Bass 159-177 

Miscellaneous Fresh- Water Fishes 179-191 

Minor Trouts and the Grayling 179 

Lake Herring and other Whitefishes 180 

Muskellunge 181 

Yellow Perch 182 

Striped Bass and White Perch 185 

Alewives or Eiver Herrings 186 

Smelt 188 

Golden Ide 188 

Sturgeons 189 

The Cod 193-207 

The Common Mackerel 209-213 

The Flatfish or Winter Flounder 215-218 

Miscellaneous Salt-Water Fishes 219-227 

Tautog 219 

Spanish Mackerel 220 

Haddock, Pollock, and other Gadidse 222 

Cunner 223 

Scup 223 

Sea Bass 223 

Squeteagues k 224 

Sheepshead 224 

Sea Herring 225 

Sand-dab and Four-spotted Flounder 227 

The American Lobster 229-238 

The Transportation of Fish and Fish Eggs 239-244 

Spawning Seasons of Fishes Propagated, Character of Fish 

Eggs, Period of Incubation, etc 245-247 

Notes on the Edible Frogs of the United States and their 

Artificial Propagation 249-261 

< (ysters and Methods of Oyster-Cnltnre 263-338 

Notes on Clam-Culture 339-340 



LIST OF ILLUSTRATIONS. 



Plate To face 

number. page 

1. Clackamas (Oregon) Salmon Station 5 

2. Figure of a Fish, showing the parts usually referred to in Descriptions 6 

3. Oncorhynchus tschaioytscka. Quinnat Salmon ; Chinook Salmon ; King Salmon 7 

4. Oncorhynchus nerka. Blueback Salmon; Redfish 11 

5. Oncorhynchus kisutch. Dog Salmon 13 

6. Salmo gairdneri. Steelhead 13 

7. Eack for stopping ascent of Salmon at Battle Creek, California 15 

8. Engine-house and Hatchery at Baird ; Current- wheel and Piers for holding Rack 19 

9. Current-wheel for pumping water at Baird, California 21 

10. Interior of Hatchery at Battle Creek, showing Salmon-basket 23 

11. Pens for holding ripe Fish, and Stripping Platform at Battle Creek, California 25 

12. Salmo salar. Atlantic Sabnon 27 

13. Views of Dead Brook inclosure for Salmon 31 

14. Salmon Live-car used in transporting Fish. Live-cars en route with Fish 33 

15. Salmon Bearing-troughs, Craig Brook Station, Maine 43 

16. Examining Fish for stripping. Stripping Female Salmon 45 

17. Packing Salmon Eggs. Picking out dead Eggs. Handling Egg-trays ^ 51 

18. Fungus on Salmon Egg. Fungus on Salmon Egg, bearing Reproductive Organs. Reproduc- 

tive Organs of Egg Fungus , , 63 

19. Taking Spawn of Landlocked Salmon at Grand Lake Stream, Maine 67 

20. Salmo irideus. Rainbow Trout : 71 

21. View of Wytheville Station, showing Breeding Ponds, with Hatchery in the background 73 

22. Spawning Pond 74 

23. Interior view of Wytheville Hatchery, showing men picking out dead Eggs 77 

24. Trout Rearing-ponds at "Wytheville Station 79 

25. Rearing-pond 81 

26. Salvelinus fontlnalis. The Brook Trout 91 

27. Trout Ponds, Northville, Michigan 93 

28. Selecting and stripping ripe Trout, Northville, Michigan 95 

29. Interior view of Northville Hatchery 97 

30. Removing green Eggs from Shipping- trays. Packing eyed eggs, Northville 101 

31. Cristivomer namaycush. Lake Trout 103 

32. Collecting lake-trout spawn on fishing steamer in Lake Michigan 105 

33. Goregonus clupeiformis. Common Whitefish 119 

34. Stripping a Whitefish 122 

35. View of Battery for hatching Whitefish 127 

36. Alosa sapidissima. Common Shad 133 

37. 38, and 39. Plates showing the development of young Shad 136 

40. Main deck of steamer Fish Hawk, equipped for hatching Shad 143 

41. Interior of Hatchery at Battery Station, equipped with Hatching-jars 151 

42. Battery Station Hatchery. Fish Commission car loading fish at Neosho 158 

43. Microptcrus salmoides. Large-mouth Black Bass 159 

44. Micropterus dolomieu. Small-mouth Black Bass 159 

45. Pomoxis annularis. Crappie 163 

46. Pomoxis sparoides. Calico Bass ; Strawberry Bass 163 

47. Ambloplites rupcstris. Rock Bass 163 

48. Bass and Trout Ponds at Neosho, Missouri 167 

49. Bass Ponds at San Marcos, Texas 173 

50. Salmo mykiss. Black-spotted Trout 179 

51. Argyrosomus artedi. Lake Herring ; Cisco 181 

52. Gadus callarias. Cod 193 

53. Stripping Cod on Vessel 196 

54. Gloucester Station 198 

55. Pool for retaining Brood Fish at Woods Hole 200 

56. McDonald Tidal-boxes, used for hatching Cod and Flatfish 202 

57. Chester boxes 204 

58. Scomber scombrus. ' Common Mackerel 209 

59. Pseudopleuronectes americanus. Flatfish or Winter Flounder 215 

60. Tautoga onilis. Tautog 219 

61. Homar us americanus. The American Lobster 229 

62. Interior of Transportation Car 239 

. 3 



4 LIST OF ILLUSTRATIONS. 

Plate To face 

number. page 

I. Anatomy of the Oyster 276 

II. Salinometer and Salinometer Cap 282 

JLLI. Ground-plan and section of Ponds for Spat-culture 323 

IV. Details of Filter for Ponds used for Oyster-culture 330 

V. Inner and Outer Paces of Shell of Typical American Oyster 340 

VI. Views of Valves of Pacific Oyster 340 

VII. Development of Oyster 340 

VJLLI. Views of Oyster Embryos 340 

IX. Set of Oysters on Shell, showing crowding 340 

X. Oyster Spat, 2 or 3 weeks old, on inside of Oyster Stiell 340 

XI. Oyster Spat about 2 months old, on a Stone 340 

XII. Oysters, 1, 2, and 3 years old 340 

XIII. Oysters 4 and 5 years old 340 

XIV. 1, Photo-micrograph of Diatom. 2, Food of South Carolina Oyster 340 

XV. 1, Urosalpinx cinerea. 2, Mytilus edulis. 3, Sabellaria vulgaris. 4, Fulgur carica 340 

XVI. Starfish attacking Oysters 340 

XVII. Bunch of Oysters, showing Growth of Mussels and Barnacles 340 

XVIII. 1, Crepidula fornicata. 2, Crepidula plana. 3, Crepidula convexa. 4 and 5, Anomia 

glabra. 6, Pecten irradians. 7, Oyster attached to pebble 340 

FIGURES IX TEXT. 



Gravel Filter 

Wire Filter 

Trough arranged for Eggs 

Longitudinal section of case of Atlantic 

Salmon Eggs 

Atlantic Salmon recently hatched 

Troughs arranged for rearing 

Stand of troughs for rearing Atlantic 

Salmon 

Hatching-troughs, Guard-screen, etc 

Cross-section through box aftei it has been 

packed and closed 

Egg-tray 

Foundation -board 

Ice-hopper 

Egg-trays packed and cleated 

Outside case 

Floating box 

Clark- Williamson trough 

Pans used in cleaning Eggs 

Shad-hatching Table 

Automatic Shad -hatching Jar 

Application of a Measuring Scale to a Jar 

of Shad Eggs 



84 
84 
85 
85 
86 
107 
110 
148 
149 
150 



Plan of Neosho Station, showing shape and 
depth of ponds, with location of Hatchery 

and Superintendent's Dwelling 166 

Artificial Nest for rearing Black Bass (per- 
spective and sectional views) 171 

Ovary of Yellow-perch, with nearly ripe 

Eggs '. 183 

Part of a recently hatched mass of Yellow- 
perch Eggs 183 

Diagram of Tidal Cod Hatching-box 202 

Spring Frog or Leopard Frog {Sana vire- 

scens) 255 

Green or Spring Frog (Rana clamata) 256 

Figures illustrating relative size of the 

Tympanum in the two Sexes 257 

Common Bullfrog (Rana eatesbiana) 258 

Western Frog {Rana pretiosa) 259 

Western Bullfrog (Rana aurora) 259 

Anatomical figure of the Oyster 278 

Tangle and Tackle 315 

Drill-dredge in position for work 316 

Drill-dredge open for emptying" 317 

Receptacle for Cultch 324 



Report U. S. F. C. 1 897. (To face page 5.) 



Plate 1. 




A MANUAL OF FISH-CULTURE, BASED ON THE METHODS OF 
THE UNITED STATES COMMISSION OF FISH AND FISHERIES. 



INTRODUCTION. 

The work of tlie United States Commission of Fish and Fisheries 
is carried on at twenty-five stations or hatcheries located at suitable 
places throughout the country. At Woods Hole and Gloucester, Massa- 
chusetts, cod, mackerel, lobster, and other important marine species are 
propagated and the fry are deposited on the natural spawning-grounds 
along the coast. At Battle Creek, Baird, and Hoopa Valley in Califor- 
nia, at Clackamas in Oregon, and Little White Salmon River in Wash- 
ington, the eggs of the* Pacific salmon are collected and hatched, and 
the fry are planted on the spawning-beds in the neighboring streams. 
The Atlanti'c and landlocked salmons are cultivated in Maine at Craig 
Brook and Green Lake to restock the depleted streams and lakes of 
New England and northern New York. On the Great Lakes at Cape- 
Vincent, New York ; Put-in Bay, Ohio ; Alpena, Michigan, and Duluth, 
Minnesota, the work is with whitefish and lake trout, in order to sustain 
the great commercial fisheries conducted for those species. Hatcheries 
in the interior at St. Johnsbu'ry, Vermont; Wytheville, Virginia; 
North ville, Michigan ; Manchester, Iowa; Bozeman, Montana; Neosho, 
Missouri; Quincy, Illinois; San Marcos, Texas, and Leadville, Colo- 
rado, are devoted to the important work of maintaining in the inland 
lakes and streams the supply of brook trout, rainbow trout, black bass, 
crappie, and other fishes. During the spring, on the Potomac, Dela- 
ware, and Susquehanna rivers, shad are hatched and are distributed 
in suitable streams along the Atlantic Coast. 

For the distribution of fish and eggs the Commission has four cars 
specially equipped with tanks, air-circulating apparatus, and other 
appliances. 

In the prosecution of marine work three vessels are used, the steamers 
Albatross and Fish HawJc ,a,nd a schooner, the Grampus. The Albatross 
is fitted with appliances for deep-sea dredging and collecting work, and 
is used for surveying and exploring ocean bottoms and investigating 
marine life. The Fish Hawk is in reality a floating hatchery, and is 
engaged in hatching shad, lobsters, and mackerel, in collecting eggs, 
and in distributing fry, besides making topographic surveys of fishing- 
grounds, etc. . 

The necessity for a handbook describing the manner of propagating 
the different fishes reared by the United States Commission of Fish 
and Fisheries has long been felt in the Commission, and it is thought 

5 



6 REPORT OF COMMISSIONER OP PISH AND FISHERIES'. 

that such a manual will be of value to all persons interested in fish- 
culture. The material for the present work has been furnished by 
experienced fish-culturists connected with the Commission, who have 
treated of the subjects with which they were especially familiar. Owing 
to the interest shown in the cultivation of oysters and frogs, special 
reports on these subjects have also been incorporated. 

The following is a list of the contributors and their subjects: 

Charles G. Atkins, Superintendent U. S. F. C. Station, Craig Brook, Maine. 

The Atlantic and Landlocked Salmons. 

F. M. Chamberlain, Assistant, U. S. Fish Commission, Washington, D. C. 

Edible Frogs and their Artificial Propagation. 

Frank N. Clark, Superintendent U. S. F. C. Stations in Michigan. 

The Brook Trout and the Lake Trout. 

J. Frank Ellis, Superintendent of Car Service, U. S. F. C, Washington, D. C. 

Transportation of Fish and Fish Eggs. 

H. F. Moore, Assistant, U. S. Fish Commission, Washington, D. C. 

• Oysters and Methods of Oyster- Culture. 

William F. Page, Superintendent U. S. F. C. Station, Neosho, Mo. 

The Black Basics, Grapples, and Bock Bass. 

George A. Seagle, Superintendent U. S. F. C. Station, Wytheville, Va. 

The Bainbow Trout. 

Livingston Stone, Superintendent U. S. F. C. Station, Baird, Cal. 

The Salmons of the Pacific Coast. 

J. J. Stranahan, Superintendent U. S. F. C. Station, Put-in Bay, Ohio. 

The Whitefish. 

Stephen G. Worth, Superintendent U. S. F. C. Station, Washington, D. C. 

The Shad. 

The chapters on the lobster and most of the minor fishes were fur- 
nished by Dr. Hugh M. Smith. 

Valuable information on marine fishes was also furnished by Lieut. 
Franklin Swift, U. S. N., C. G. Corliss, E. E. Hahn, Alexander Jones, and 
E. F. Locke, of the United States Fish Commission, and on the quinnat 
salmon by J. P. Babcock, of the California State Fish Commission. 

In order to increase the usefulness of the work to the general reader, 
a technical description of each important fish is given, together with 
brief information regarding its geographical distribution, habits, move- 
ments, size, growth, food, natural spawning, etc. 

While the operations described are essentially those of this Com- 
mission, they are usually the same as those employed by the State 
commissions and individual fish-culturists, although, in some instances, 
excellent work is done by other methods. The propagation of the 
various marine species is carried on only at the Government hatcheries. 
The methods described for hatching Salmomdce, while differing in 
minor particulars, are practically interchangeable, and may be used at 
the discretion of the fish-culturist. 

John J. Brice, 

Commissioner. 



Report U. S. F. C. 1 897. (To face page 6.) 



Plate 2. 




Report U. S. F. C. 1897. (To face page 7.) 



Plate 3. 



..:■'' ..'..,-:',:' MM 




s a 



THE SALMONS OF THE PACIFIC COAST. 



There are five species of salmon on the Pacific coast which belong 
to the genus Oncorhynchus, namely, the chinook or quinnat salmon 
(Oncorhynchus tschawytscha), the red or blueback salmon (Oncorhynchus 
nerka), the humpback salmon ( Oncorhynchus gorbuscha\, the silver 
salmon [Oncorhynchus Jcisutch), and the dog salmon (Oncorhynchus Iceta). 
The features which separate the Pacific salmons from the Atlantic salmon 
are not marked and consist chiefly in a larger number of rays in the 
anal fin, and more branchiostegals, gillrakers, and pyloric coeca. 

The characters noted in the following key will usually be sufficient to 
distinguish the different species of Pacific salmon: 

Quinnat salmon : Scales in longitudinal series from 135 to 155, aver- 
aging about 145; pyloric cceca 140 to 185; gillrakers comparatively 
short and usually 23 in number, 9 being above the angle; rays in anal 
fin 16; branchiostegals 15 to 19. Body robust; head conic; eye small; 
caudal fin deeply forked. Color above dusky, sometimes with bluish or 
greenish tinge ; sides and belly silvery; head dark, with metallic luster; 
back and the dorsal and caudal fins with numerous round black spots. 

Blueback salmon: Scales in longitudinal series about 130; pyloric 
cceca, 75 to 95; gillrakers comparatively long and 32 to 40 in number; 
rays in anal fin 14 to 16; branchiostegals 13 to 15. Body rather slen- 
der; caudal fin much forked; anal and dorsal fins low. Color, above 
bright blue, sides silvery, no spots. 

Humpback salmon : Scales very small, 210 to 240 in longitudinal series; 
pyloric cceca very slender, about 180 in number ; gillrakers short, about 
28, 13 being above angle; anal rays 15; branchiostegals 11 or 12. 
Color, bluish above, silvery on sides; hind part of back, adipose fin, and 
tail with numerous black spots, largest and of oblong form on tail. 

Silver salmon : Scales large, 125 to 135 in longitudinal series ; pyloric 
cceca comparatively few and large, 45 to 80 in number ; gillrakers long 
and slender, 23 in number, 13 below angle; anal rays 13 or 14; branchi- 
ostegals 13 or 14. Body long; head short, conic; snout blunt; eye 
small; fins small, caudal deeply forked. Color bluish-green, sides sil- 
very, finely punctulated ; spots few and obscure on head, back, dorsal, 
adipose dorsal, and upper rays of caudal. 

Dog salmon: Scales of medium size, 138 to 155 in lateral line; pyloric 
cceca 140 to 185; gillrakers short and few, 9 above and 15 below angle; 
13 or 14 rays in anal fin; branchiostegals 13 or 14. Form of quinnat, 
but head longer and more depressed. Dusky above and on head, paler 
on sides; very fine spots on back and sides, often wanting; tail plain 
dusky or finely spotted, with black edge; other fins blackish. 



8 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 

These salmons are the most important group of fishes entering the 
rivers of North America. The steelhead (Salmo gairdneri), technically 
a trout, but popularly regarded as a salmon, also inhabits the waters 
of the Pacific coast and adds to the importance of the salmon tribe. 

In recent years the average annual catch of salmon in the Pacific 
States and Alaska has been about 100,000,000 pounds, with a first 
value of about $2,800,000 ; as placed on the market, in a fresh, salted, 
or canned condition, the value is about $5,700,000. The yearly catch of 
about 25,000,000 pounds of salmon in British Columbia, having a value? 
when prepared, of $2,500,000, raises the approximate annual value of 
the Pacific salmons to $8,200,000. 

THE QUINNAT SALMON. 

The quinnat salmon (Oncorhynchus tschaioytscha) is known by a 
number of other common names in various parts of its range; among 
them are chinook salmon, king salmon, Columbia salmon, Sacramento 
salmon, tyee salmon, and saw-qui. The quinnat is the most important 
of the salmons. It is not only superior in food qualities, but attains a 
vastly larger size, has a wider geographical range, and has greater 
commercial value than all the others. When fresh from the ocean it 
is a very handsome, resplendent, well-formed fish, greatly resembling 
the Atlantic salmon (Salmo solar), although its form is less symmet- 
rical and its outlines less graceful. The flesh is of a uniform rich red 
color, becoming paler or streaked at the approach of the spawning 
season. The great value of the fish for canning purposes is largely 
due to the persistence of the red color of the meat after cooking. 

In size no other salmon in the world compares with it. In the 
Yukon Eiver, Alaska, it reaches a weight of over 100 pounds, and in 
the Columbia Eiver there are well-authenticated cases of its weighing 
more than 80 pounds. Farther south it runs smaller, although in the 
Sacramento individuals weighing 50 or 60 pounds are not rare; 22 
pounds is a fair average weight in the Columbia Eiver, and 16 pounds 
in the Sacramento. 

The known range of the quinnat salmon is practically from Monterey 
Bay (latitude 36 J) to Yukon Eiver, although individuals have been seen 
in Norton Sound, somewhat north of the Yukon, and as far down the 
coast of California as Ventura Eiver. Since it thrives well in very cold 
water it is likely that its range extends to and possibly within the 
Arctic Ocean. 

While in the sea quinnat salmon probably do not wander very far 
from the mouths of the rivers they have left, and for this reason usually 
return to spawn in those rivers in which they were hatched. They 
prefer the larger rivers, like the Sacramento, the Columbia, the Nusha- 
gak, and the Yukon. They are very persistent in ascending the rivers 
to spawn; the first fish take up the first available spawning-sites and 
force the newcomers farther up stream, until finally the highest points 
are reached. They have been seen crowding up the rivulets which form 



MANUAL OF FISH-CULTURE. 9 

the headwaters of the Sacramento until nearly half their bodies were 
exposed to the air. No matter how far the headwaters of a river are 
from the ocean, some of the salmon will press forward until stopped 
by impassable obstructions or water too shallow for them to swim in. 
On reaching the headwaters they remain for a week or two before 
proceeding' to the spawning-grounds. Their rate of progress varies with 
the season, and probably depends to a great extent on the rainfall and 
the state of the river, rain, roily water, and high water always hastening 
their progress. 

When they first come from the ocean the sexes are almost identical 
in appearance, but as the time for spawning approaches a difference is 
noticed between the males and the females, which during the spawning 
season becomes more marked. The fully developed ova of the female 
give her a round, plump appearance, while the male grows very thin ; 
his head flattens, the upper jaw curves like a hook over the lower, the 
eyes become sunken; large, powerful, white, dog-like teeth appear on 
both jaws, and the fish acquires a gaunt and savage appearance. As 
soon as they reach fresh water their appetites grow less, their throats 
begin to narrow, and their stomachs to shrink. This does not at first 
entirely prevent them from feeding, but it changes them enough to 
enable them to overcome the temptation to return to their well-stocked 
feeding-grounds in the ocean, and the longer they remain in fresh water 
the greater are the changes, and the -desire to turn back for food is 
correspondingly lessened. This change comes about gradually, increas- 
ing day by day from the time they leave tide water until at the near 
approach of the spawning season their throats and stomachs become 
entirely incapacitated for receiving food, and the desire and ability to 
feed leave them entirely. The great reserve of flesh and blood which they 
bring with them from the ocean enables them to keep the vital organs 
active until their mission up the fresh-water streams is accomplished. 

Quinnat salmon that spawn a long distance from the ocean do not 
return to it again, but die on or near their spawning-grounds. This 
singular fact has been disputed, but its truth has been proved repeat- 
edly and conclusively. After spawning they 'rapidly deteriorate, the 
flesh shades off to a light, dirty pink and they become foul, diseased, 
and very much emaciated through wounds and great exertion. Their 
scales are wholly absorbed in the skin, which is of a dark olive or 
black hue, and blotches of fungus appear on their heads and bodies, 
and in various places are long white patches where the skin is partly 
worn off. Their fins and tails become badly mutilated, and in a short 
time they die exhausted. 

The quinnat salmon first appear on the Pacific coast at Monterey Bay, 
where many are caught with hooJt and line as early as the second week 
in January, and are next seen in the Sacramento River in numbers in 
February. In the Columbia River they appear in March, but are not 
abundant until April or May. They arrive in southern Alaska in 
May and farther north in June, while it is probable that it is still later 



10 EEPORT OF COMMISSIONER OF FISH AND FISHERIES. 

before they ascend the Yukon, where the running season is very short 
and may not exceed a month or six weeks. The early runs in the 
Columbia Eiver are usually from one to three weeks passing from the 
mouth of the river to Clifton, about 20 miles. They first appear at 
The Dalles, 200 miles up the river, in the middle of April, and are found 
in great quantities at this point about the middle of June, two months 
after they appeared in large numbers at the bar. This would indicate 
that they proceed up the Columbia at the rate of 100 miles a month. 
In the later runs they probably travel faster. 

The spawning season of the quinnat salmon varies in different rivers, 
and, considering the entire coast, extends over a period of fully six 
months. In July the summer run is spawning at the headwaters of 
the McCloud and Sacramento; in August and September, farther down 
these rivers. In October the fall run has begun at the McCloud 
and below, and this run continues spawning through November into 
December. In the Columbia the spawning season begins at the head- 
waters in June; at Clackamas, 125 miles from the mouth of the river, 
it begins about the middle of September and continues until November. 

A few days before they are ready to spawn the salmon hollow out 
elongated cavities with their heads and tails in the gravel beds of the 
river where there is some current, and here in due time the eggs and 
milt are deposited. The eggs drift into the crevices in the pile of 
stones thrown up below the hollow, sink to the bottom, and remain in 
that protected position during incubation ; here, also, the young remain 
until the umbilical sac is absorbed. The eggs and young are liable to 
destruction by freshets, but are comparatively safe from other injurious 
influences. 

The quinnat salmon is not so prolific as the Atlantic salmon, 300 or 
400 eggs to each pound weight of the parent fish being about a fair 
average. 

In view of the enormous annual destruction of this salmon for com- 
mercial purposes the necessity for its propagation became manifest at 
an early period in the history of the Pacific fisheries. Fortunately the 
species is readily susceptible of artificial propagation on a large scale. 
In 1873 the application of fish-cultural methods to this species began 
on the McCloud Eiver, California. The propagation work, since grown 
to large proportions, now engages the attention of all the coast States 
as well as the general government, and in 1896 was more extensive 
than ever before. Whenever large numbers of the fry, artificially 
hatched, have been placed in the waters of the Pacific coast, whether 
in the tributaries of the Sacramento or the Columbia, an increase in the 
run of full-grown fish has been observed after the time required for a 
salmon to mature (about four years) has elapsed. 

As the salmon ascend the rivers they are caught by gill nets, pounds, 
weirs, fyke nets, seines, wheels, and other devices, but the great bulk 
of those taken in the Columbia and Sacramento are caught with gill 
nets drifting with the current or tide as they head up stream. In the 



Report U. S. F. C. 1 897. (To face page 1 1 .) 



Plate 4. 




MANUAL OF FISH-CULTURE. 11 

rivers they are comparatively safe from enemies except otters, ospreys, 
and fishers, but immense numbers are destroyed at the mouths of the 
streams by seals and sea lions. 

The quinnat salmon has been successfully introduced into Australia, 
New Zealand, and France, and in the latter country it is now being 
reared successfully as landlocked salmon in fresh-water lakes. Efforts 
to acclimatize this species on the Atlantic coast of the United States 
have up to this time been unsuccessful. 

THE BLUEBACK SALMON. 

Considering the entire west coast, this species ( Oncorhynclius nerJca) 
is probably more numerous than all the other salmons combined. It is 
known in different regions under the names blueback, redfish, red 
salmon, Eraser Eiver salmon, and sock-eye or saw-qui. It ranks next 
to the chinook in commercial value, being especially important in the 
Columbia and Fraser rivers and in Alaska. For canning purposes it 
is but little inferior to the chinook, the color of the flesh being a rich 
red, which persists after canning. Comparatively few red salmon are 
sold fresh in the United States. Large quantities are canned in British 
Columbia and in Alaska, particularly on Kadiak Island, and its com- 
mercial importance to that Territory is indicated by the fact that nearly 
half of the entire salmon pack of the world comes from Alaska and the 
majority of the fish canned are of this species. 

It is next to the smallest of the salmons, the maximum weight being 
about 15 pounds, but it rarely weighs over 8 pounds and the average 
weight is scarcely 5 pounds. In various lakes this fish weighs only 
half a pound when mature, and is called the little redfish. 

It ranges from Humboldt Bay, California, to the far north. In 
general it ascends only those rivers which rise in cold, snow-fed lakes. 
No more is known of its ocean life than of the quinnat. It appears 
in the Columbia Eiver with the spring run of the quinnat salmon. In 
southern Alaska and also at Kadiak Island it comes in numbers in 
June; the heaviest run is during June and July, the spawning occur- 
ring in August and September. In the Idaho lakes, which may be 
considered typical spawning-grounds for this fish in the United States, 
the height of the spawning season is from August 25 to September 5, 
although ripe eggs have been found as early as August 2, and fish with 
eggs in them as late as September 11. In the numerous affluents of 
the Fraser Eiver the spawning extends from September 15 to November 
15, a few stragglers spawning as late as November 30. They scoop out 
small circular nests for their eggs in rather shallow water in the inlets 
of the lakes, where they deposit their spawn, the eggs averaging about 
1,000 to 1,200 to the fish. 

Except during the breeding season the color of this fish is a clear 
bright blue above, with silvery sides and belly. At the spawning 
period the back becomes blood-red in color, the sides dark red, and the 
male develops an extravagantly hooked jaw. 



12 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 

THE HUMPBACK SALMON. 

The humpback salmon (Oneorhynchus gorbuscha) is the smallest of 
the Pacific salmons; its average weight is only 5 pounds, and it is rarely 
found weighing as much as 10 pounds. Its geographical range is from 
San Francisco probably as far north as the Mackenzie Biver, and it 
is also common on the Asiatic coast. It is the most abundant and 
generally distributed salmon in Alaska, but in the Pacific States it 
does not ordinarily occur in great abundance, although there is some- 
times a noteworthy run in the Puget Sound region. 

In food value the fresh-run humpback is scarcely inferior to any other 
salmon. While the flesh has a very fine flavor, it is paler than that of 
other red salmon, and the species has consequently been neglected by 
canners. It is probable, however, that it will eventually be utilized for 
canning purposes, and its excellent qualities when fresh are undoubtedly 
destined to give it a great commercial value. The chief consumption 
now is by Alaskan natives, who cure large quantities for winter use. 

The humpback salmon generally seeks the smaller streams for the 
purpose of spawning and deposits its eggs a short distance from the 
sea, sometimes within only a few rods of the ocean. At Kadiak Island, 
Alaska, where it is often very abundant, it arrives in the latter part of 
July, the run continuing only a few weeks. Spawning takes place in 
August. There are only a few hundred eggs to each fish, the eggs 
being smaller than those of the quinnat but larger than those of the 
redfish, and paler in color than the eggs of either of those species. 

When this salmon first comes from the ocean it resembles a small 
quinnat, but as the spawning season advances it develops a very large 
and prominent hump on its back. This, with the distortion of the jaws, 
gives the fish a very singular appearance. The extreme emaciation and 
the extensive sloughing of the skin and flesh, which are incident to 
spawning, result in the death of all the fish, either on the spawning- 
grounds or after being swept out to sea by the current. 

THE SILVER SALMON. 

This fish ( Oncorhynclms Msutch) is known as silver salmon, silversides, 
skowitz, kisutch, hoopid salmon, and coho salmon. It is a beautiful 
fish, having a graceful form and a bright silvery skin. The flesh, which 
is fairly good, usually has a bright red color, but owing to its fading 
on cooking it is not highly regarded for canning purposes, although 
large quantities are thus utilized in the Columbia Eiver, Puget Sound, 
and in the short coast streams of Oregon and Washington. Its average 
size in the Columbia and Puget Sound is 8 pounds, but in Alaska the 
average is nearly 15 pounds. It rarely reaches 30 pounds in weight. 
Its range is from San Francisco to northern Alaska, and as far south 
on the Asiatic coast as Japan. It runs up the rivers to spawn in late 
fall or early winter, when the waters are high, but does not ascend 
great distances from the ocean. The average number of eggs to a fish 
is about 2,000. 



Report U. S. F. C. 1897. (To face page 13.) 



Plate 5. 




Report U. S. F. C. 1897. (To face page 13.) 



Plate 6. 




MANUAL OF FISH-CULTURE. 13 

THE DOG SALMON. 

The dog salmon (Oncorhynchus Jceta) is the least valuable of the 
Pacific salmons, although it is dried in large quantities by the Alaskan 
natives. Its average weight is 12 pounds and the maximum is about 
20 pounds. It is found from San Francisco to Kamchatka, being 
especially abundant in Alaska. The enlargement and distortion of 
the jaws give the species a very repulsive look. When just from the 
ocean, the flesh has a beautiful red color and is not unpalatable, but it 
deteriorates rapidly in fresh water. Larger quantities are utilized in 
Puget Sound than elsewhere in the Pacific States. 

THE STEELHEAD. 

Another anadromous salmonoid fish found on the Pacific coast, popu- 
larly regarded as a salmon, is the steelhead (Salmo gairdneri), known 
also as Gairdner's trout, hardhead, winter salmon, square-tailed trout, 
and salmon trout. It resembles in form, size, and general appearance 
the salmon of the Atlantic coast, and is distinguished from other Pacific 
coast salmon by its square tail in the spawning season, its small head, 
round snout, comparatively slender form, light-colored flesh, and its 
habit of spawning in spring. It is more slender than the quinnat and 
consequently not so heavy for its length. The average weight in the 
Columbia is about 10 pounds, although sometimes a weight of 30 
pounds is attained. 

Its range is very extended, reaching from Santa Barbara on the 
southern coast of California to the Alaska Peninsula, and perhaps to 
the Arctic Ocean, and it is found in almost all the streams of the 
Pacific States which empty into the ocean. It begins to enter the 
Columbia in the fall, and is then in prime condition „ From this time it 
deteriorates until the following spring, when, between the months of 
February and May, spawning occurs. The fish's movements in other 
rivers on the coast are not materially different, though perhaps it enters 
the southern rivers earlier and the northern rivers later than the 
Columbia. Like the chinook, the steelhead ascends rivers for long 
distances, and it has been found almost as far up the tributaries of the 
Columbia as the ascent of fish is possible. The eggs are much smaller 
than those of the quinnat salmon and average 3,000 to 5,000 to the fish. 

As the greatest quantities of steelheads are caught in the spring, 
when they are spawning and in a deteriorated condition, they are not 
generally esteemed as food. When they come fresh from the sea and 
are in good condition, however, their flesh is excellent. As the demand 
for salmon has increased, steelheads have been utilized for canning 
and they have formed a noteworthy part of the canned salmon from 
the Columbia Eiver for a number of years past, as well as from the short 
coast rivers of Washington and Oregon. Their consumption fresh has 
been increasing yearly and considerable quantities have been sent to 
the Eastern States in refrigerator cars. 



14 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 

ARTIFICIAL PROPAGATION. 

The chinook being the principal salmon that has been propagated 
artificially, the following chapter is devoted almost entirely to this 
species. The discussion of the apparatus and methods has special 
reference to the hatcheries of the United States Fish Commission on 
the McGloud Eiver and Battle Creek, tributaries of the Sacramento, 
although cognizance is also taken of the work at the stations in the 
basin of the Columbia Eiver and on the short coast rivers of California 
and Oregon. 

In 1896 the number of eggs of this fish collected by the Commission 
was 3G,237,000, from which about 32,000,000 fry were hatched and 
planted. The collections of eggs of the silver salmon numbered 298,137, 
which yielded 298,000 fry, and of steelhead eggs 604,000, which pro- 
duced 499,690 fry. 

CAPTURING- ADULT SALMON. 

The adult salmon from which eggs are obtained for the purposes of 
propagation are taken chiefly with drag or sweep seines, this being 
the most practical method of collecting them in large numbers. The 
seines at the United States Fish Commission station at Baird, on the 
McCloud Biver, are from 120 to 170 feet long, made of about 28-thread 
twine, and are 20 feet deep in the middle, tapering down to about 
6 feet at the ends; they are double-leaded on account of the swift 
current of the river, and have a 4-inch mesh. In the rack placed 
across the river to stop the passage of fish it is customary to build 
large wooden traps in which to capture salmon, and at times, espe- 
cially during a rain storm accompanied by a marked rise in the river, 
large numbers of salmon are taken, but at other times only a few, 
while there is never more than a small percentage of spawning fish 
secured in this way. 

The trap is quite a valuable auxiliary to the seine, but can not be 
relied on exclusively. Although it will secure many unripe fish, the 
ripe ones, which are the ones that are wanted, finding an obstruction 
in their way, settle back to spawning-grounds below and remain there. 
The trap is simply a square inclosure of vertically placed slats, with 
an entrance similar to that of an ordinary pound net. The fish in 
their eager efforts to pass upstream, go through the V-shaped mouth of 
the trap, and having once entered, are not able to find their way out. 
Boards are placed over the top of the trap to prevent the fish from 
leaping out. 

Large dip nets have been used occasionally at Clackamas station, in 
Oregon, the fishermen standing on the rack at night and dipping below 
it. Toward the end of the season this method secures a considerable 
number of ripe fish, but it involves much labor and expense, and most 
of the spawning fish taken with the dip nets would probably have been 
captured in the regular course of fishing. There being no satisfac- 
tory seining-grounds at Clackamas, and the river just below the rack 



Report U. S. F. C. 1 897. (To face page 1 5.) 



Plate 7. 





MANUAL OF FISH-CULTURE. 15 

being shallow, an Indian method of fishing is used. The aversion of 
salmon to heading downstream is well known, but when they are very 
much frightened they will turn around and rush downstream at their 
utmost speed. The Indians take advantage of this fact and build a 
dam of rock or wickerwork, or anything that will present an obstruc- 
tion to the frightened fish. It is shaped like the letter V, with the angle 
downstream, and at the angle is a large trap into which the fish are 
driven. This was at one time the principal method of capturing the 
breeding salmon at Clackamas, and it worked very satisfactorily. Fyke 
nets and other fish-catching devices have been employed from time to 
time, but have been rejected as unsatisfactory. 

At Baird, before the rack was employed permanently, seine fishing 
was usually begun after dark and continued throughout the night, but 
since the rack has been in use the seine has been hauled more or less 
in the daytime with perfectly satisfactory results, the fishing generally 
commencing about 4.30 a. m. and continuing as long as the results war- 
rant it. The work is resumed again about 5 o'clock in the afternoon 
and continued as long as it meets with success. 

RACK FOR CLOSING THE STREAM. 

The rack employed as a barricade against the ascending salmon 
consists of a fence placed across the river and supported by piers heavy 
enough to prevent the force of the current from pushing them out of 
position. Log stringers, from 8 to 15 inches in diameter, are laid from 
pier to pier, to which they are securely pinned, and posts, from 2 to 4 
inches in diameter and of the required length, are driven obliquely 
into the bed of the river, the lower ends being 3 or 4 feet upstream, 
the upper ends resting on the stringers. Against these posts is laid the 
rack, which is made in sections, each 6 to 10 feet long, the slats which 
form them being 1^ inches thick and 3 inches wide, and securely 
braced at top and bottom. The slats are set 1£ inches apart, and are 
beveled on the upper side in order to present less resistance to the 
current. The space between the slats allows ample room for the water 
to go through, but prevents any salmon from ascending. A wider space 
between the slats would be preferable, as creating less obstruction to 
the current, but it would allow a considerable percentage of small grilse 
(the young salmon after its first return from the sea) to get by the rack, 
and unless males are quite plentiful the grilse are likely to be needed 
when the spawning season arrives. 

The piers, when first made, are hollow triangles of heavy logs, each 
layer of logs being firmly pinned to the one below it, until the required 
height is reached, the apex of the triangle pointing upstream. They 
are afterwards filled with rocks and are very substantial. Those on the 
McCloud have been able to withstand the tremendous momentum of the 
current, even in the highest water. 



16 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 

TAKING AND IMPREGNATING THE EGGS. 

After salmon are secured by the seine or other means, they are, for 
convenience in handling, placed in pens or live-boxes made for this 
purpose, the ripe or nearly ripe males and females being kept separate. 
Where the eggs are taken on a large scale, it is desirable to have 
separate compartments for ripe males, ripe females, nearly ripe females, 
and males partially spent that it may be necessary to use again, and 
one or two spare compartments are found to be convenient where large 
numbers of fish are handled. 

Stripping the fish is usually done every day, as the eggs of the 
females confined in the pens are likely to be injured within the fish, 
which is a serious objection to keeping the parent fish in confinement 
any longer than is absolutely necessary. 

Of the signs that usually accompany ripeness in a female salmon, 
the separation of the eggs in the ovaries is the surest, but the specific 
signs are all fallible, and the spawn-taker relies rather on an indescrib- 
able ripe look, which is neither color, shape, nor condition of organs, 
but a general appearance which shows at a glance that the fish is ripe, 
and can be appreciated only by experience. 

When taking the eggs, one or two men stand ready with dip nets to 
hand the females to the spawn-taker, and one or more perform the same 
office with the males. After the salmon are taken from the pens they 
are held suspended in the net until their violent struggles are over, 
after which they become quiet enough to be handled and the eggs and 
milt can be expressed easily. 

All methods of taking salmon spawn are very much the same, there 
being only slight differences in details, chiefly in the manner of holding 
the parent fish and impregnating the eggs. Where there are plenty 
of assistants and the salmon are of medium size, the most expeditious 
way is for the man who takes the spawn to hold the female in one 
hand and press out the eggs with the other, another in the meantime 
holding the tail of the fish. The male fish is handled in the same way. 
This is the method employed at Baird, but on the Columbia, where the 
salmon are larger and harder to manage, the "strait-jacket," as it is 
called, is used; this is a sort of trough made the average length of the 
salmon and hollowed out to fit its general shape. Across the lower end 
is a permanent cleat, and at the upper end is a strap with a buckle. 
The fish, when manipulated, is slid into the trough, the tail going down 
below the cleat, where it is securely held and the head buckled in at 
the upper end with the strap. It is now unable to do any harm by its 
struggles and the eggs can be pressed out at leisure. The strait-jacket 
is almost indispensable with very large salmon and is very convenient 
when the operators are limited in number. 

In impregnating the eggs the main object is to bring the milt and 
the eggs together as quickly as possible after they have left the fish. 
By some persons a little water is considered desirable to give greater 
activity to the milt, but if left more than a minute in the water there 



MANUAL OF FISH-CULTURE. 17 

is a decided loss of fertilizing power. The eggs do no,t suffer so quickly 
from immersion in water. The absorbing property which they possess 
when they first leave the parent fish, and which attracts to the 
micropyle the spermatozoa, lasts several minutes, but it is not prudent 
to leave the eggs in the water a moment longer than is necessary before 
adding the milt. 

The addition of the water is not essential to a good impregnation; 
in some instances better results are secured without the use of water 
and, after all, if the main object is secured, of bringing the milt and 
the eggs together with the slightest possible delay after they leave the 
fish, it makes very little difference whether water is used or not. 
The milt retains its fertilizing power several days when kept from air 
and water, and impregnation can be effected between fishes widely 
separated by merely forwarding the milt properly sealed. At Baird 
impregnation by the dry method, which has always been followed there, 
has resulted in the fertilization of about 90 per cent of the eggs so treated. 

The Russian or dry method of impregnating eggs consists simply in 
taking both the eggs and the milt in a dry pan. It may be urged as 
an objection to this method that the eggs will be injured by striking 
against the dry pan, but it is a fact that although the same eggs would 
be destroyed by the concussion a week afterwards, or even twenty-four 
hours afterwards, they do not suffer in the least from it at the moment 
of extrusion from the fish. 

It was at one time considered an important question whether the 
eggs or milt should be taken first, but with the dry method it makes 
no difference, as, either way, both eggs and milt remain operative long 
enough for all practical purposes of impregnation. 

Various methods of treating the eggs in the pan after impregnation 
has taken place have been tried, and all apparently with about the 
same results. Some operators leave the eggs in the pans as first taken 
with the milt for two or three inmates and then add water, after which 
they are left to stand in the pan until they separate, when they are 
washed clean, taken to the hatching-house, and placed in the troughs. 
Others pour the contents of the several pans — eggs, milt, and all — into 
a large can, after they have remained in the pans just long enough to 
become impregnated. When the eggs separate the contents of the can 
are poured into the hatching-troughs just as they are, trusting to the 
current in the troughs to wash the milt from the eggs. Where the 
water supply is scant and the current sluggish in the trays, the best 
method is to wash the milt thoroughly from the eggs before placing 
them in the hatching-trays, as the milt will foul the water if it remains 
in the troughs. 

The methods employed in taking and fertilizing eggs at Clackamas 
station are as follows : The female fish to be operated upon is taken 
from a floating pen and placed in the spawning-box or "straight- 
jacket"; a male fish is then caught and tied with a small rope auound 

F. C. E. 1897 2 



18 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 

its tail to some part of the corral where he can be quickly caught when 
needed. One man presses the eggs from the female securely held in 
the spawning-box, the pan for receiving these being held by another. 
As soon as the eggs are taken, the male is drawn from the pen by the 
rope and held by one man, who takes it by the tail with his left hand, 
its head between or across his knees. With his right hand the milt 
is then pressed from the fish into the pan containing the eggs as soon 
as possible after they are taken. The eggs are taken in a pan without 
any water and milt enough is used to insure its coming in contact 
with each egg. After the eggs and milt are obtained the pan is gently 
tilted from side to side aud the mass of eggs and milt stirred with the 
lingers until it is thoroughly mixed. The pan is then filled about two- 
thirds full of water and left until the eggs separate, the time varying 
from 1 to 1£ hours, according to the number of eggs and the condition 
of the atmosphere. 

After the eggs cease to stick to each other and to the sides of the pan 
they are washed clean by repeated rinsings and taken to the hatching- 
house, where they are measured and put in troughs. The percentage 
of eggs impregnated varies with different seasons, places, and methods 
of handling, but it is safe to say that 90 per cent of the eggs taken are 
impregnated. 

The eggs of the quinnat salmon are of a deep salmon-red color. They 
are heavier than water. Their size varies somewhat, but averages about 
tV or tS °f an i ncn 5 from 12 to 18 are covered by a square inch. The 
number in a quart is about 3,700. 

HATCHING APPARATUS AND METHODS. 

The hatching apparatus generally employed on the Pacific coast in 
salmon propagation consists of a combination of troughs and baskets. 
The troughs in common use are the so-called "Williamson troughs," 
which are 16 feet long, 12 or 16 inches wide, and 6£ inches deep. The 
troughs are arranged in pairs, and usually two or three pairs are placed 
end to end on different levels. The fall of water in each trough is 1£ 
inches. The troughs are divided by double partitions of wood or metal 
into compartments just enough longer than the baskets to enable the 
latter to be raised and lowered and to be tilted slightly. The essential 
feature of these troughs is thait at the lower end of each compartment 
a partition, extending entirely across the trough, reaches from the 
bottom almost to the top, and another similar partition at the upper 
end of the compartment reaches from the top almost to the bottom of the 
trough, each set of partitions being about an inch apart. The water 
is consequen tly forced to flow under the upper partition and over the 
lower partition, and in order to do this it must necessarily ascend 
through the tray of eggs The troughs are provided with covers made 
of canvas stretched upon light frames, and made sunlight proof by 
saturation with asphaltum varnish. The interior of the troughs is 
thickly coated with asphaltum. 



Report U. S. F. C. 1897. (To face page 19.) 



Plate 8. 




MANUAL OF FISH-CULTURE. 19 

The egg receptacles are deep wire trays or baskets about 12 inches 
wide, 24 inches long, and deep enough to project an inch or two above 
the water, which is 5 or 6 inches deep in the troughs in which they are 
placed. Into each of these baskets 2 gallons of salmon eggs, equiva- 
lent to about 30,000, are poured at a time. The eggs suffer no injury 
whatever from being packed together in this manner, the water being 
supplied in a way that forces it through the eggs, partially supporting 
and circulating through them. The meshes are too small to permit the 
eggs to pass through, although the fry are able to do so. 

The advantages of this apparatus and method are: 

(1) The top of the tray or basket is out of the water and always 
entirely dry; consequently, in handling it, the hands are kept dry. 

(2) By tilting one end of the tray up and down a little or by lifting 
it entirely and settling it gently back again in its place the bad eggs 
will be forced to the top; thus a feather is not required in picking over 
the eggs and the injuries very often inflicted with it are avoided. 

(3) The top of the tray being above water, the eggs can never run 
over the top nor escape in any way, which is a great advantage over 
the shallow form of tray. 

(4) There is economy of space; 30,000 to 40,000 eggs can be placed 
in each basket, provided a sufficient quantity of water is available. 
Two troughs, 16 feet long and 1 foot wide, will by this method carry 
about 500,000 salmon eggs. The deep trays may be filled at least half 
full of eggs, and thus ten times as many eggs can be hatched in the 
same space and with the same supply of water as by the old method. 
A good but gentle circulation is continually maintained through the 
eggs. 

(5) The deep-tray system is admirably adapted to getting rid of mud 
that has collected on the eggs, for all sediment accumulating about 
them can be easily removed by gently moving the tray up and down a 
few times in the water j but if the deposit of mud on the troughs 
becomes so excessive as to be unmanageable, a false bottom of wire 
cloth or perforated zinc can be placed in the troughs at a suitable 
distance above their real bottom, leaving a space of about 1 or 1J inches 
between the wire cloth and the trough bottom. By this means the mud 
that comes into the trough will sift down into the space below the wire 
cloth entirely out of the way of the fish, the movements of the fish 
themselves helping very much to produce this result. Should the 
accumulation of mud in the space below the false bottom of the trough 
become too great, it can easily be sluiced out in various ways. 

When quinnat- salmon eggs are simply to be matured for shipment, 
hatching-trays with ^ or } inch square mesh will answer the purpose, 
but when the eggs are to be hatched in them, every alternate strand of 
wire running lengthwise, or, better still, every second and third thread, 
should be left out in order to form an oblong mesh through which the 
newly hatched fry, after separating themselves from the unhatched 
eggs ? can escape from the hatching- trays into the troughs below. 



20 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 

At Baird eggs kept in water averaging about 54° F. hatch in 35 days. 
The allowance of 5 days' difference in the time of hatching for each 
degree of change in the temperature of the water is approximately 
correct. 

For the first few days the eggs of the quinnat salmon are very hardy, 
and at this time they should be thoroughly picked over and the dead 
ones removed as far as possible before the delicate stage during the 
formation of the spinal column comes on, so that during that critical 
period they may be left in perfect quiet. As soon as the spinal column 
and the head show plainly, the eggs are hardy enough to ship, but when 
there is time enough it is better to wait a day or two until the eye-spot 
is distinctly visible, after which time the eggs will stand handling. 

PACKING EGGS FOR SHIPMENT. 

The packing-box used in shipping salmon eggs is made of £-inch 
pine, 2 feet square and 1 foot deep. At the bottom is placed a thick 
layer of moss, then a layer of mosquito netting, then a layer of eggs, 
then mosquito netting again, then successive layers of moss, netting, 
eggs, netting, and so on to the middle of the box. Here a firm wooden 
partition is fastened in and the packing renewed above in the same 
manner as below. The cover is then laid on the top, and when two 
boxes are ready they are placed in a wooden crate, made large enough 
to allow a space of 3 inches on all sides of the boxes. This space is 
filled with hay to protect the eggs against changes of temperature, and 
when the cover is put on the eggs are ready to ship. 

In the middle of the crate an open space about 4 inches in depth is 
left, between the two boxes of eggs, for ice. As soon as the crates 
arrive at the railway station this space, as well as the top of the crate, 
is filled in with ice. Eecent experiments show that salmon eggs can be 
packed and safely transported to considerable distances when they are 
first taken. 

CARE OF THE FRY. 

The eggs of quinnat salmon, like those of other Salmonidce, hatch 
very gradually at first, only a small proportion of fish coming out the 
first day. The number increases daily, however, until the climax of 
the hatching is reached, when large numbers of the young burst their 
shells in a single day. At this time great care and vigilance are 
required. The vast number of shells rapidly clog up the guard-screens 
at the outlet of the troughs, which should be kept as free as possible 
by thoroughly cleansing them from time to time. 

M the deep trays the newly hatched fish are mixed with unhatctied 
eggs, and the advantage of the oblong mesh in the bottom of the trays 
becomes apparent. This mesh is too narrow to allow the eggs to fall 
through, bu«t the hatched fish, being comparatively long and narrow, 
easily slip down through the long meshes into the space below. They 
should be assisted in accomplishing this by gently raising and lowering 



Report U S. F. C. 1897. (To face page 21.) 



Plate 9. 




CURRENT-WHEEL FOR PUMPING WATER AT BAIRD, CALIFORNIA. 



MANUAL OF FISH-CULTURE. 21 

the tray at intervals, care being taken not to raise them out of the 
water, as at this tender age a slight pressure against the wire of the 
tray will often produce fatal injuries. On this account too much caution 
can not be exercised in regard to handling them out of water during 
the first stages of the yolk-sac period, for the injuries can not be seen 
at first, and often the death of the fry is the first warning that they 
have been injured. 

After the eggs are all hatched and the young fish are safely out of 
the trays and in the bottom of the troughs their dangers are few and 
they require comparatively little care. Almost the only thing to be 
guarded against now is suffocation. Even where there is an abun- 
dance of water and room, with a good circulation, they often crowd 
together in heaps or dig down under one another until some of them die 
from want of running water which is not an inch away from them. The 
best remedy in such a case is to thin them out. 

Eight thousand gallons of water an hour is sufficient for ten lines of 
troughs 64 feet in length, containing altogether a little over 1,000,000 
young salmons in the yolk-sac stage. This gives in round numbers 
800 gallons of water to each 100,000 fry every hour, or 16§ gallons per 
minute, which is a safe minimum. 

When the yolk-sac has become nearly absorbed the fish rise from the 
bottom of the trough, where they have previously remained, and hold 
themselves up in the water. It is now almost time to begin to feed 
them, and they have become comparatively hardy and require very 
little care- 
Close attention is required again, however, as soon as they commence 
to feed. They will show when they are ready to feed by darting to one 
side or the other when small particles of food are dropped in the water 
and floated past them. From this time, for several weeks, the necessity 
for care and vigilance never ceases. 

The young fish should, for the first few weeks, be fed regularly and 
as often as six times a day, and the earlier in the day the feeding begins 
and the later it continues at night the better. Two hours after feeding 
they will be found to be ravenously hungry, and they grow much faster 
for frequent feeding and get that growth in their infancy which is 
indispensable to their ultimately attaining the largest possible size. If 
they are not fed very often they will bite at one another's fins and so 
cause more or less mortality among themselves. 

ARTIFICIAL FOOD. 

The best food for salmon fry is some kind of meat, finely pulverized. 
Boiled liver is especially good for this purpose, partly because it is 
inexpensive and easily obtainable, and also because it can be separated 
into very fine particles. Eaw liver is also an excellent food for fry, 
and may be reduced into as fine particles as the cooked liver by grind- 
ing or chopping and then properly straining it through a fine-mesh 



22 REPORT OP COMMISSIONER OP PISH AND FISHERIES. 

screen. The yolk of boiled eggs is also suitable, but it is comparatively- 
expensive and is not so good for the fish as liver unless largely mixed 
with it. 

As the fish grow older they continue to thrive best on meat food, but 
if that is not always obtainable in sufficient quantities or on account 
of its expense, a very good substitute is a mixture of shorts or corn 
meal with the meat. This is prepared as a mush by stirring shorts or 
middlings into boiling water, a little at a time, so that it will not cook 
in lumps, but become more of a paste. After it has thoroughly cooked 
it is allowed to cool and harden. The best proportion is 30 pounds of 
shorts to 25 gallons of water with 3 or 4 pounds of salt. The per- 
centage of liver to be used in this mixture should be regulated by the 
age of the fish, feeding the very young fry upon almost a simple meat 
diet and increasing the proportion of mush with the age of the fish. 

Doubtless for young Salmonidw the best natural fish food, not arti- 
ficially bred, is the roe of fishes which have minute ova, as the best 
food for the mature fish is live minnows. These foods furnish the fish 
with a clean, suitable diet and leave no decaying matter on the bottom 
of the troughs or ponds to foul them or produce disease. But these 
foods can rarely be obtained without too much expense, although the 
time will undoubtedly come when perch, carp, and similar coarse fish 
will be economically propagated and raised to serve as food for trout 
and salmon. Herring roe is now canned for fish food, and if this can 
be furnished at a sufficiently low price it may ultimately provide an 
excellent food for young salmon. 

PLANTING THE FEY. 

The most prominent instinct of the newly-hatched salmon is to burrow 
for concealment, and this habit persists until the necessity for active 
feeding compels them to come from their hiding-places. The retention 
of salmon in troughs for a number of months after they begin to feed 
naturally leads to a considerable change in their instincts and makes 
them less liable to escape from their enemies after being planted. The 
fry are liberated on the natural spawning-grounds, as a rule, as soon 
as the umbilical sac is exhausted and they show a disposition to feed 
at the surface, When, for any reason, the fry are held longer, their 
growth varies in accordance with the character and temperature of the 
water in which they are reared and the food they receive. The young 
fry reared at Baird station grow to a length of 2£ inches from the time 
when they begin to feed in February until the middle of May, when, 
on account of the rising temperature of the water, they are liberated in 
the McCloud River. 



Report U. S. F. C. i 897. ^To face page 23 ) 



Plate 10. 




MANUAL OF FISH-CULTURE. 23 

SALMON-HATCHING AT BATTLE CREEK. 

While the manner of taking and impregnating salmon eggs differs 
but little at the hatchery of the United States Fish Commission at 
Battle Creek, California, from that at other places, the magnitude of 
the operations warrants separate description. 

This is now the most remarkable salmon-propagating station in the 
world, the total number of eggs secured for hatching during the season 
of 1896 being 25,852,880, which is about 15,000,000 more than have 
been taken hitherto at any one station. This phenomenal take of eggs 
would have been still larger had not a flood washed away the rack 
and allowed the heavy run of salmon to pass upstream. 

This station is situated near the mouth of Battle Creek, a tributary 
of the Sacramento, and although less than 40 miles below Baird station, 
receives the fall run of salmon only, while at Baird this run is light as 
compared with the summer run. 

Immediately above its confluence with the Sacramento, Battle Creek 
is deep and lagoon-like for a distance of 2\ miles, and salmon gather 
there in vast numbers before entering the shallow waters where their 
spawning-grounds commence. At the head of the lagoon is a retaming- 
rack similar to that in use at Baird, the fish being taken with a seine 
just below it. 

During the heavier part of the run 500 or 600 are taken at each 
sweep of the seine, the number at times being more than can be hauled 
in. The first eggs were taken in 1896 on October 8, and collection con- 
tinued until the breaking of the rack on November 23, at which time 
the run of fish was still in progress. Five thousand "ripe" females 
were taken, averaging 18 pounds in weight. No record was kept of the 
males, as more could always be taken than were required, but those 
retained were used day after day until exhausted. Male salmon out- 
numbered the ripe females 3 to 1. 

Spawning operations are conducted upon a floating platform 24 feet 
long and 12 feet wide, beneath which are nine compartments for retain- 
ing the ripe fish, and which are accessible through hinged covers set 
in the plank flooring. Projecting beyond this platform is another, upon 
which the actual work oi stripping the fish and caring for the pans is 
performed. It is roofed with tarpaulin, and on three sides is inclosed 
with burlap. 

The taking of spawn is performed by ten men. The method differs 
but little from that at Baird, except in the manner of handling the fish 
and the regular use of water in the spawning-pan. One pint of water 
is placed in the pan before either the eggs or the milt. Two men take 
the females from the compartments in dip nets and hold them until 
taken out by the spawn-takers, not allowing them to strike the floor dur- 
ing their struggles. The female is held by two men, one taking the fish 
from the dip net by the tail, and the other by the head. The stripper 
then comes between them as the fish is held over the spawning-pan and 



24 REPORT OF COMMISSIONER OP FISH AND FISHERIES. 

presses out the eggs. One man dips the male fish from their com- 
partment and places them on the floor of the platform directly behind 
the two men who handle them. One holds the flsh by the head and the 
other presses out the milt with one hand as he holds it by the tail with 
the other, the milt falling into the same pan that receives the eggs and 
practically at the same time. 

The eggs and milt are gently stirred with a feather in the spawning- 
pan as they are expressed from the flsh, and the pan is then placed 
upon a shelf under a dark curtain, where it remains for 1£ minutes, 
when the contents are poured into a large galvanized iron bucket nearly 
full of water, the eggs being placed therein before adhesion takes place. 
During the season of 1896 a total of 4,968 females were stripped, 
producing 25,852,880 eggs. The greatest number of females stripped 
in any one day was 269, yielding 1,392,000 eggs. The spawning crew 
became very proficient, having stripped as many as 151 females in 60 
minutes. Spawning usually takes place during the afternoon and 
seldom exceeds 2£ hours of active work. 

The eggs are transferred by wagons from the spawning platform to 
the hatcheries in large galvanized-iron buckets, 15 inches deep and 14 
inches in diameter, which, when filled with water, hold about 70,000 
eggs. The tops of the buckets are covered with canvas, and the 
average length of time occupied in taking the eggs, transferring tliem 
to the hatcheries, and measuring them into the hatching-baskets is 40 
minutes. 

The two hatcheries at Battle Creek contain 160 hatching-troughs, 68 
of those in the building first erected being 16 feet by 16 inches by 6£ 
inches, while half of the 92 in the other building are of the same size, 
the remainder being 16 feet by 12 inches by 6£ inches. A head or 
distributing trough runs lengthwise of each building and receives the 
water from the settling-tank on the outside. The hatching- troughs are 
arranged in sections of four bound together. Two abut against the 
distributing-trough, from which they take their supply of water and 
carry it to the two troughs below, whence it passes to the escape 
drain at their lower ends; 24 gallons of water per minute are admitted 
to each trough, and the average temperature of the water is 52°. At 
the head of each hatching -trough, 2 inches above the surface of the 
water, is placed a tin aerator, 10 inches by 4 inches by 1J inches, the 
bottom only being perforated; 4 inches from the lower end of each 
trough a retaining-screen is placed at an angle. Between the screen 
and the end there is a 2-inch hole in the bottom stopped with a plug 
which projects above the surface of the water. In cleaning the trough 
this plug is removed, the increased flow of water causing a strong 
current through the entire length of the trough, which has a capacity 
of 200,000 eggs contained in five trays or baskets. 

When the eggs reach the hatchery they are washed, measured, and 
placed in the hatching baskets or trays, 40,000 being placed in the 
16-mch and 25,000 in the 12-mch trays. These are made of galvanized 



Report U. S. F. C. 1897. (To face page 25.) 



Plate 1 1 . 




MANUAL OF FISH-CULTURE. 25 

iron wire, with meshes | by £ of an inch, fastened at the top to a wooden 
frame | inch thick. They are 23 inches Jong, 15A inches wide at top, 
15 inches at bottom, and 6 inches deep. When placed in the hatching- 
trough the wooden frame of the basket rests on the edge of the trough. 

Two division plates of galvanized iron are placed in the hatching- 
trough just above each basket. The first one rests on the bottom 
and extends to within an inch of the surface of the water; the second is 
placed half an inch below the first one, and extends from the top of the 
box to within an inch of the bottom. This causes an upward current of 
water to pass through the eggs, which, however, is not strong enough 
to move them. 

From the second to the tenth day the eggs are washed and the dead 
eggs are picked out, but from the tenth to the fifteenth day they are 
not handled in any manner, no matter how much sediment may cover 
them. After the fifteenth day, or when the young fish is well defined 
in the egg, washing and picking is renewed and continued daily until 
the eggs are packed for shipment. 

The method of handling is determined by the conditions, a lower 
temperature allowing them to be washed beyond the tenth day, but 
the above noted is the average for the season of 1896. The total loss 
in eyeing (that is, carrying eggs from time of taking until the eye- 
spots appear) during the season was 1,308,290, or 5.06 per cent. No 
eggs were hatched at Battle Creek station, as the water supply was 
considered unsafe. 

In packing eggs for shipment no ice is used except for long distances. 

The eggs received at the Sisson station of the California Fish Com- 
mission, located at the headwaters of the Sacramento River, are treated 
by methods similar to those already described as being used at Battle 
Creek. The average number of days taken to hatch the eggs is 42, 
and the alevins absorb the sac in from 30 to 40 days at an average 
temperature of 44°. After the eggs are hatched, the division plates 
resting upon the bottom of each trough are removed and the remaining 
plates lowered to within half an inch of the bottom of the hatching- 
trough. This divides the trough into sections and results in a stiff 
current running under each plate, which prevents the massing of the 
alevins at the head of the trough. At this time, a A-shaped piece of 
galvanized iron, termed a harbor plate, is placed in each trough 4 inches 
above theretaining-screen, with its apex against the current; it extends 
to within an inch of each side of the trough and rises to the surface of 
the water. The water in passing around each end of the plate causes 
an eddy that carries the weak alevins away from the screen into the 
angle of the plate, affording them a harbor of rest and preventing their 
being held against the screen. 

The loss of alevins while absorbing the sac is slight. The space for 
hatching-troughs at Sisson is limited; and to relieve the troughs the 
planting of alevins begins a few days after they hatchj hence the exact 



26 REPORT OP COMMISSIONER OE PISS AND FISHERIES. 

percentage of loss can not be given; but the total loss of alevins at 
the hatchery the past season was 32,934, or 0.3 per cent, in a total of 
10,000,000. The loss after feeding began was very slight, amounting 
only to 5,716. 

The alevins and the fry of the Pacific salmon possess great vitality 
and are less liable to disease than those of any of the other Salmonidw. 

The natural conditions for hatching, rearing, and planting fry at the 
Sisson hatchery are excellent; the water supply is unlimited and is 
very free from sediment, even during stormy weather, while it has an 
equable temperature, averaging 52° for the year, seldom falling to 40° 
or exceeding 60°. 

No part of the hatching- house work requires more attention or is of 
such vital importance as the cleaning of the troughs. Up to the time 
that the alevins begin to feed the troughs should be thoroughly cleaned 
once every day by rubbing them down with the hand covered with a 
coarse crash mitten, and after they begin feeding the troughs require 
much more attention. One hour after each meal the troughs should 
be cleaned by passing a bunch of stiff feathers over the sides and 
bottom, first removing the division and harbor plates and the plug at 
the foot of the trough. 



Report U. S. F. C. 1897. (To face page 27j 



Plate 12. 



mm m> 

mum i f-mff 







THE ATLANTIC SALMON. 



DESCRIPTION OF THE FISH. 

The body of the Atlantic salmon ( Salmo salar) is moderately elongate 
and but little compressed ; the greatest depth is about one-fourth the 
total length without the caudal fin. The length of the head is about 
equal to the body depth. The mouth is of moderate size, the maxillary 
reaching just past the eye, its length contained 2 £ or 3 times in the 
head. The scales are comparatively large, becoming embedded in adult 
males; the number in the lateral line is about 120, with 23 above and 
21 below that line. The dorsal fin has 11 rays and the anal 9 rays. The 
pyloric cceca number about 65. 

The color, like the form, varies with sex, age, food, and condition. 
The adult is brownish above and silvery on the sides, with numerous 
small black spots, often x or xx shaped, on the head, body, and fins, 
and with red patches along the sides in the male. Young salmon (parrs) 
have about 11 dusky crossbars, besides black and red spots. 

RANGE. 

The salmon native to the rivers of the northeastern United States is 
specifically identical with the salmon of Europe and all the affluents of 
the North Atlantic. Its original natural range in America appears to 
have been from Labrador or Hudson Bay on the north to the vicinity of 
New York on the south. Within these limits, at the proper season of the 
year, it ascended, for the purpose of reproduction, nearly every river 
except those that did not afford the requisite facilities for depositing 
spawn or were inaccessible by reason of impassable falls near their 
mouths. 

In American rivers frequented by Atlantic salmon they were found 
successively in all parts from the mouth upward, their migrations extend- 
ing nearly to the headwaters of all the branches so far as they were 
accessible and adapted to their necessities. The one exception is the 
river St. Lawrence, where it seems probable, from such evidence as is 
available, that few if any salmon entering the river from the sea ever 
ascended as far as Lake Ontario, and that the salmon inhabiting that lake 
and its tributaries have always, as a rule, made the lake their sea and 
the limit of their downward migrations. Within or partly within the 
limits of the United States there can be enumerated twenty-eight rivers 
that were beyond doubt naturally frequented by salmon, beginning witu 

27 



28 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 

the St. John and ending with the Housatoiiic* In the greater part 
of these the speeies has been exterminated by civilized man, and in 
the few in which it still persists its numbers are far below the estimates 
which the earliest records warrant us in making for those days. 

In certain lakes of Maine and northward this fish is perfectly land- 
locked and has somewhat different habits and coloration, but no distinct 
specific characters. Similar landlocked varieties occur in Europe. 

LIFE AND HABITS. 

Salmon eggs are deposited on coarse gravel on some rapid, generally 
far up toward the sources of a river, late in October or early in Novem- 
ber, when the water is perhaps about 44° F. and the temperature is 
falling. The egg is impregnated at the moment of its deposit, and the 
independent life of the salmon begins to develop at once. In a few 
weeks the embryo becomes sensitive, but the extreme cold of the water 
retards its development to such an extent that it does not burst the 
shell of the egg until spring. In the rivers of New England it is prob- 
able that nearly all the eggs naturally deposited hatch very late in 
April and early in May. At this time the embryo salmon has a slender 
half-transparent trunk, less than an inch in length, carrying, suspended 
beneath, an immense ovoid sac — the "yolk-sac." For about six weeks 
after hatching it hides in crevices among stones, keeping up an inces- 
sant fanning with its pectoral fins. During this period it takes no food, 
but is supported and nourished by the yolk-sac, the substance of which 
is gradually absorbed into the rest of the body, and not until the sac 
has nearly disappeared does the salmon really look like a fish and begin 
to seize and swallow food. It nbw puts on a mottled coat, with several 
heavy dark bars across its sides, and bright red spots, larger and fewer 
than those of a trout, looking therefore very unlike the adult salmon 
but much like a young trout. In this stage it is termed, in Scotland 
and England, a "parr," and it was formerly thought to be a wholly 
different species from salmon. 

The parr stage lasts a year or two in British rivers, and the few 
observations made in America indicate that it is more likely two years 
than one in our rivers. The parr, at first but little over an inch in 
length, is provided with good teeth and a good appetite, and beginning 
to feed at a season of the year when the water is almost crowded with 
small insects and other more minute creatures, it grows rapidly, prob- 
ably increasing its weight thirty or forty times the first summer. In 
two years it reaches the length of 6 or 8 inches, and its bright red 
spots and dark bars have given place to a silvery coat like the adult 
salmon. It is now termed a " smolt" and is ready to go to sea, which 
it does with little delay, and passes out beyond the range of man's 

*The Hudson River is by some believed to have been a natural salmon river. Its 
discoverer, Hendrick Hudson, reported having observed them there, and there is 
nothing inherently improbable in it, but the evidence is perhaps insufficient. 



MANUAL OF FISH-CULTURE. 29 

observation, but to a region where it finds a rich, feeding- ground and 
rapidly increases in size.* In northern rivers, those of New Brunswick 
and beyond, as in those of northern Europe, the salmon returns from 
the sea when it has attained a weight of 2 to 6 uounds, and is then 
termed a "grilse." 

In the rivers of Canada, m general, grilse occur in great numbers, 
coming in from the sea at a later date than the adults, but ascending 
like them to the upper waters, mingling freely with them, rising to the 
same fly, and caught in the same weirs. The mesh of the nets is limited 
by law to a size that takes the adult salmon, but allows the grilse to 
slip through. To this circumstance it is in part owing that by the 
time the fish have reached those portions of the rivers suitable for 
angling there is commonly, if it be late enough in the season, a great 
preponderance of grilse, so that more of the latter than of the former 
are taken by the angler. In Nova Scotia many grilse are taken in the 
Shubenacadie Eiver from August until late in the fall. On the Mirami- 
chi, in New Brunswick, grilse make their appearance about July 1, and 
from the middle of that month till the end of August they constitute 
the main body of the salmon entering the river. Some sportsmen 
report that the grilse caught exceed the adults in the ratio of 5 to 1. 

In the month of August, in the Nepissiguit, Restigouche, and St. 
John of Gasp6, grilse have been found in some years to exceed the 
adults in the ratio of 3 to 1. They run into the Nepissiguit mostly 
between July 25 and September 1. Their scarcity during the early part 
of the angling season, or say previous to July 20, is attested by numer- 
ous fishing scores. A series of scores of salmon fishing in the Godbout 
River, on the north side of the St. Lawrence, shows that previous to 
July 15 or 20 the adult salmon taken with the fly in that river exceed 
the grilse in the ratio of 10 to 1 or more. 

In our rivers grilse are seldom seen, and only 3 or 4 are taken per year 
in a weir in the St. Croix, which takes about 70 adults. In the Dennys 
River the ratio of grilse to salmon caught is not more than 1 to 500, and 
in the Penobscot they are cpiite as rare. Adult salmon running in this 
river several weeks earlier than in those of eastern New Brunswick, we 

* There lias been considerable discussion on this point, and the conclusions of some 
observers are at variance with the above statement. In Scotland many years ago it 
seemed to be well established by the observations of Buist tbat a portion of the young 
salmon put on the silvery coat and went to sea at the age of one year, but that others 
of the same brood did not get ready to go until two years old. American observa- 
tions, however, tend strongly to the conclusion that the young salmon passes two 
whole 'summers in the river, going out to sea in the autumn following its second 
summer or the nest spring. It is not probable that the seaward migration is 
restricted in any river to any exact period of a few weeks duration, but that it 
extends over many months, some of the young salmon, by reason of superior native 
vigor of growth or from other equally efficient cause, attaining the migratory stage 
months earlier than others of the same brood. 

It is the opinion of one American observer that salmon fry remain in the streams 
until October of the second year before going to sea, and that they do not go down 
until the spring of the third year; i. e., when they are two years old; though some 
may go down the fall of the second year; and that the salmon do not return 'until 
they are four years old. 



30 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 

should naturally expect the advent of grilse early in July in considerable 
numbers; but some of the weirs are often kept in operation until the 
middle or last of July, and sometimes even through August, when they 
take menhaden ; but no grilse enter them. During the latter part of the 
summer the water at the several falls between Bangor and Oldtown is 
generally at a low stage, and the attempt of grilse, even in small num- 
bers, to ascend the river could hardly fail to be frequently detected. 
A similar state of things exists in the Kennebec. There is no escaping 
the conclusion that the great run of grilse, which is so prominent a fea- 
ture in the history of the salmon of northern rivers, is almost entirely 
wanting in the rivers of the United States. It by no means follows from 
this that our salmon do not pass through the same phases of growth, or 
that the growth is more rapid, but merely that when in the grilse stage 
they generally lack the instinct that inrpels their more northern relatives 
to seek fresh water. 

Of the characteristics of grilse, as ascertained in the rivers they 
frequent, it will be sufficient to say that they exhibit to a great degree 
the characteristics of the adult; that the main external differences 
are a shorter head, slenderer form, and a difference in the color and 
markings; that they are remarkably active and agile, leaping to great 
heights; that the male is sexually well developed and mates with the 
adult, but that the female is immature, and that, like the adult, they 
abstain from food and consequently lose flesh during their stay in fresh 
water. 

The next stage of life of the fish is that of the adult salmon, and this 
is the stage at which, with the exceptions indicated above, the Atlantic 
salmon first ascends the rivers of the United States. Assuming that it 
relinquished the rivers for the sea at the age of two years, being then 
a smolt, it has been absent two years, and it is now four years or a little 
more since it burst the shell. This estimate of age is based on the 
observations made by the Massachusetts commissioners of fisheries 
on the return of salmon to the Merrimac River, which plainly estab- 
lished the fact that the entire period between the hatching of the fry 
and the return of the adult to the rivers is about four years. Whether 
the same rule holds in other New England rivers can not as yet be 
established, owing to deficient data, but the presumption is in favor of 
that conclusion. In Canadian rivers the same period of growth appears 
to be the universal rule, at least as far north as the St. Lawrence Eiver. 
Statistics of the catch of salmon for many years in eighteen separate 
districts, showing many fluctuations, exhibit a remarkable tendency of 
the figures to arrange themselves in periods of five years; thus, the 
year 1875 having been a year of small catch of salmon, it also appears 
in most of the districts that the next year of abnormally small catch 
was 1880. Now, the eggs laid in 1875 would hatch in 1876, and the 
young hatched at that time would be grown in 1880, requiring thus 
four years from hatching to maturity, just as on the Merrimac. It 
Would seem no other interpretation can be put upon the statistics, 



Report U. S. F. C. 1897. (To face page 31.) 



Plate 13. 




ENTRANCE TO DEAD BROOK INCLOSURE FOR SALMON. 



V 









DEAD BROOK INCLOSURE FOR ATLANTIC SALMON, SHOWING PENS. 



MANUAL OF FISH -CULTURE. 31 

EARLY SALMON-CULTURE ON THE PENOBSCOT RIVER. 

The movement for the reestablishment of the fisheries for salmon, 
shad, and other anadromons species in American rivers originated in 
the action of the legislatures of New Hampshire and Massachusetts, 
having in view primarily the fisheries of the Merrimac and Connecti- 
cut rivers. The course of the Connecticut lies partly in the State of 
Connecticut, while many of its tributaries are in the State of Vermont, 
and these two States were therefore early interested in the project, and 
their action soon led to a similar movement on the part of Ehode Island 
and Maine. The rivers within the borders of these six States are the 
only ones in the United States known to have been frequented by the 
seagoing Salmo salar, except possibly the Hudson and certain rivers 
tributary to the St. Lawrence, in the northern part of New York. 

The commissioners to whom the governments of the above States 
confided the task of restocking the exhausted rivers turned their 
attention at once to the two most important of the migratory fishes, the 
salmon and the shad. The utter extermination of salmon from most 
of the rivers compelling the commissioners to consider the best mode of 
introducing them from abroad, eggs were obtained for a time from the 
spawning-beds in the rivers of Canada and hatched with a measure of 
success. After a few seasons permits for such operations were discon- 
tinued, and it became essential to look elsewhere for a supply of salmon 
ova. In 1870 attention was directed to the Penobscot Eiver, in the 
State of Maine, which, though very unproductive compared with Cana- 
dian rivers, might yet, perhaps, be made to yield the requisite quantity 
of spawn. The fisheries are all in the lower part of the river and in 
the estuary into which it empties, Penobscot Bay, and there the supply 
of adult salmon could be found with certainty, but they must be obtained 
from the ordinary salmon fisheries in June and held in durance until 
October or November, and the possibility of confining them without 
interfering seriously with the normal action of their reproductive func- 
tions was not yet established. 

This plan was finally adopted, and in 1871 this method of breeding- 
salmon was first attempted. For the purpose of the experiment, a 
point at the mouth of Craig Brook, which is by water nearly 9 miles 
distant from the mouth of the Penobscot Biver, more than half the 
route being through brackish water, was selected as the most conven- 
ient fresh-water stream which offered facilities for confining the salmon 
and maturing their eggs. After some unsuccessful trials means were 
found of safely conveying a few live salmon in floating cars from the 
fishing-grounds to the station, where they were held till the spawning 
season, when their eggs were taken and impregnated. 

From 1872 to 1876 operations were conducted on a larger scale, with 
a fair degree of success, and, after a suspension, were resumed in 1879 
at Craig Brook hatchery, while the retaining inclosures were located 
in Dead Brook, about 2 miles distant. The disadvantage of this 



32 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 

distance between the hatchery and retaining-ponds was offset by other 
advantageous conditions. 

Until 1886 no attempt was made to rear salmon, and with unimpor- 
tant exceptions the work was confined to the collection of salmon eggs, 
their development during the earlier stages, and their transfer in winter 
to other stations to be hatched. In 1889, however, the United States 
Fish Commissioner decided to establish a permanent station at Craig 
Brook, and in anticipation of the purchase of the premises, which was 
concluded the following year, the rearing of salmon to the age of six or 
seven months was undertaken as the leading work of the station. 

COLLECTION OF STOCK SALMON. 

The only salmon fisheries available for the purpose of supplying Craig 
Brook station with breeding fish are those carried on by weirs about 
the mouth of the Penobscot. Arrangements are made early in the 
season with weir fishermen to save their salmon alive and deliver them 
daily to the collecting agent of the station, who makes the rounds of 
the district about low water with a small steamer, which tows the cars 
containing the fish on the flood-tide to Orland village, where they are 
passed through the lock about high water and taken by a crew of oars- 
men to the inclosure at Dead Brook. 

In anticipation of this work, the fisherman places the floor of his 
weir a little lower than he would otherwise do, so that at low water the 
salmon may have water to swim in instead of being left high and dry 
by the retreating tide, in case of an accidental delay or failure to visit 
the weir at the usual hour. It is, however, the ordinary practice to 
take the salmon out at each "fish-tide," i. e., low water, and place them 
in a car. Cars enough are stationed among the fishermen to bring one 
at least in each neighborhood, and in most cases the car is brought 
alongside and the salmon transferred to it directly from the weir, 
though in some cases it is necessary to place the salmon first in a box, 
in which it is carried by a boat to the car. The car employed is made 
from the common dory, divided transversely into three compartments. 
The central one, which is much the larger, is occupied by the fish, and 
is smoothly lined with thin boards and covered with a net to prevent 
the fish jumping out or being lost by the car capsizing, which some- 
times occurs, while to guard them from fright and the rays of the sun 
a canvas cover is drawn over all. 

The first cars of this form constructed had iron gratings to separate 
the central from the forward and after compartments, the water 
being admitted through the forward and discharged through the after 
compartment, but this was objectionable because the salmon were 
constantly seeking to escape through the forward grating, and often 
injured themselves by rushing against it. Smooth wooden gratings 
were afterwards used and for many years cars were employed in which 
the compartments were separated by tight board partitions, the open- 
ings for the circulation of water communicating through the sides of 



Report U. S. F. C. 1897. (To face page 33.) 



Plate 14. 




SALMON LIVE-CAR USED IN TRANSPORTING FISH FROM WEIRS TO DEAD BROOK. 



» i 






SALMON LIVE-CARS EN ROUTE WITH FISH, 



MANUAL OF FISH-CULTURE. 33 

the boat directly with the fish compartment and being, of course, grated. 
This was very satisfactory, but when it was found desirable and prac- 
ticable to use ice in transportation, the forward compartment became 
the ice-room, and it was necessary to perforate the partition again to 
admit the cold water to the fish. Finally, stout woolen blanket cloth 
was substituted in the partitions, with eyelet holes wrought in to afford 
passage to the water. This is the form now in use, in which the water 
is admitted through openings in the sides to the ice-room, from which 
it passes through the fish-room to the after room, whence it is discharged. 
The car is ballasted so that the rail is just above water or, in case 
of an unusually large load of fish, a little below it. All the openings 
communicating with the outside are controlled by slides, which can be 
closed so as to let the car swim high and light when it is towed empty. 

The boxes used for the transfer of salmon hold about 90 gallons each, 
and are 2 feet wide, 2 feet deep, and 3 feet long, with a sliding cover, 
in the center of which is an inch auger hole for ventilation. Such boxes 
were used at Bucksport from 1872 to 1874 to convey the salmon on 
drays from the cars to the inclosure, a distance of a little more than a 
mile; six or eight salmon were taken at once, the box being filled brim- 
ful of water, which was brackish and generally clear and cool. Though 
the largest fish could not lie straight in the box, and the time occupied 
in transit was commonly twenty minutes, they as a rule arrived at the 
pond in good condition. 

To avoid injury \ uhe fish in transferring them to the cars, fine 
minnow dip nets, lined with woolen flannel of open texture, are used. 
The bow on which the net is hung is 22 inches in diameter, and to 
secure a net of ample width three ordinary nets, 36 inches in depth, are 
cut open down one side quite to the bottom, and then sewed together, 
giving thus three times the ordinary breadth without increasing the 
depth. 

The collection of salmon is begun each season usually from the 20th 
of May to the 1st of June, but as the maximum temperature that the 
fish fresh from the weirs will endure is about 75° F., the temperature 
of the water through which the cars are towed must be taken into 
consideration, and the collection not be postponed until too late in the 
season. If the collection is prolonged, this difficulty is obviated by 
using ice, as it has been found that by moderating the volume of water 
passing through the car and introducing it all through the ice compart- 
ment it is possible to keep a uniform temperature in the compartment 
in which the fish are held several degrees below that of the water in the 
river, thereby insuring the safe transfer of the salmon. 

THE DEAD BROOK INCLOSURE. 

The principal sources of Dead Brook are two small lakes, and on 
some of the tributaries there are considerable springs. While the 
water is slightly purer than that of ordiuary brooks, it is by no means 

F. C. E. 1897 3 



34 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 

so transparent as that of Craig Brook, and the bottom can hardly be 
seen at the depth of 4 feet. This circumstance is regarded as favor- 
able. The inclosure is located on the lower stretches of the brook, not 
more than half a mile from its month, with low banks on either hand 
and a very gentle current flowing over a bed that is for the most part 
gravelly but in part consists of a peaty mud that supports a luxurious 
growth of aquatic vegetation. The general depth is less than 4 feet, 
but two of the pools are 8 feet deep and another is 6 feet deep. The 
width of the stream is from 20 to 80 feet. The inclosure occupies the 
entire stream for a distance of 2,200 feet, embracing an area of about 
2^ acres. At either end is a substantial barrier, consisting of wooden 
racks, which obstruct the current very slightly but contine the salmon 
securely. The lower barrier is provided with a gate, which swings open 
to admit boats, and at the upper barrier are located the spawning-house 
and watchman's camp and a small storehouse. 

The temperature of the water during the summer months generally 
ranges between 60° and 70° F., but the surface temperature occasionally 
rises to 76°, 80°, and even 84°. During sultry weather the temperature 
at the bottom has been observed and in the deeper pools has been found 
to be notably lower than at the surface. Thus a temperature of 75° 
at the surface has been found to be accompanied by (58° at the bottom; 
78° by 74° ; and 81° by 72°. It is probable that to the existence of these 
deeper pools the survival of the salmon through extremely hot weather 
may be ascribed. 

After their liberation in the inclosure the salmon are at first quite 
active, swimming about and often leaping into the air. This continues 
for several weeks. After that they become very quiet, lying in the 
deepest pools and rarely showing themselves until the approach of the 
spawning season. 

Most of the deaths occur during the first few weeks of their impris- 
onment, doubtless in consequence of injuries received in capture or 
during transfer, though high temperature in the inclosure itself about 
the time of the introduction of the salmon may be one of the causes of 
mortality. Fish that escape the dangers of June appear to become 
acclimated and able to endure the high temperatures of July and 
August without injury. 

Notwithstanding salmon enter the rivers in spring or early summer, 
ascending at once to their upper waters and there, in fresh water, 
awaiting the spawning season, fresh water is not essential to the activ- 
ity of their reproductive functions. At the Canadian fish-breeding 
station of Tadoussac, where salmon are almost the only fish cultivated, 
it has for many years been the practice to hold their brood fish in an 
inclosure supplied with salt water, which flows and ebbs through the 
barrier confining the salmon, and the development of eggs and milt is 
in no wise unfavorably affected, 



MANUAL OF FISH-CULTURE. 35 

WATER FOR A SALMON HATCHERY. 

The first requisite for a salmon hatchery is an ample supply of suit- 
able water, on a site where it can be brought completely under control 
and the proper tall secured. In this matter there is quite a range of 
choice. The very best is the water from a stream fed by a clean lake of 
considerable depth, taken a short distance below the outlet of the lake, 
with an intervening rapid. Craig Pond may be taken as an example of 
such a lake. It has an area of 231 acres, an extreme depth of 69 feet, 
and a depth of 25 feet within 500 feet of the outlet. The depth directly 
influences the temperature and, other things being equal, a deep lake 
will afford water more uniform in temperature than a shallow one — cooler 
in summer and warmer, though never too warm, in winter. Such water 
is commonly quite even in volume and temperature, and comparatively 
pure. It is cold in winter and warms up slowly in spring, assuring a 
slow, normal development of the eggs, which is more conducive to 
health and vigor than a quicker development. The passage down a 
rapid will further improve this water by charging it highly with air. 

After this, the water of a brook is to be chosen that is fed largely by 
springs, so as to insure constancy in the supply and some moderation 
of the temperature on warm days, but it is better to have the water 
flow a long distance in an open channel before using, and, if possible, 
over a rough and descending bed, that it may be well aerated, and in 
cold weather somewhat cooled down from the temperature with which 
it springs from the ground. 

Thirdly, choose pure spring water; but in all cases where this is 
necessary provide a cooling and aerating pond, that the original warmth 
of the water may be subdued by the cold of the air before it reaches 
the hatching-troughs, and that it may absorb more or less air by its 
wide surface. 

Lastly, choose ordinary river or brook water, as clean as possible. 
The latter are considered inferior to spring water by reason of their 
liability to floods, drought, muddiness, and foulness of other sorts, and 
in cold climates to anchor ice. Between these different sorts there is 
of course an infinite number of gradations. If lake water can not be 
obtained it would be of some advantage to have a supply of both 
spring water and brook water, depending for ordinary use on the brook 
water or a mixture of the two, and on the spring water for emergencies, 
such as the freezing, drying, or excessive heating of the brook, floods 
with accompanying muddiness, etc. Avoid water coming from boggy 
and stagnant ponds and marshes; for though excellent water, capable 
of bringing out the most vigorous of fish, may sometimes be had in 
such places, yet when not supplied by springs it is dependent for its 
freshness and good qualities upon rainfalls, and if these fail, as they 
are liable to, the water may become foul and unfit. It must be borne 
in mind that these remarks about the selection of water for fish- cultural 
purposes apply only to the culture of Atlantic or landlocked salmon,, 
in a climate like that of the State of Maine. 



36 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 

It is best to select a site for a hatching establishment in time of 
extreme drought, and if it then has an ample supply of pure, sweet 
water the first requisites are fulfilled. It is well also to visit the place 
in time of flood and, if in a cold climate, in severe winter weather, to 
learn the dangers to be guarded against on those scores. The volume 
of water necessary will depend mainly on the proposed capacity of the 
establishment, the temperature of the water, its character as to aeration^ 
and the facilities existing for the aeration and repeated use of the water. 
With water of the highest quality and low temperature, and with unlim- 
ited facilities for aeration, possibly a gallon a minute, or even less, can 
be made to answer for the incubation of 100,000 eggs of salmon. As 
the temperature rises or the facilities for aeration are curtailed a larger 
volume becomes necessary. In case of spring water, cooled only to 
40° and aerated only by exposure to air in a pool of about a square rod 
surface, with no facilities in the house for aeration, and with the eggs 
and fry crowded in the troughs at the rate of 4,000 per square foot, 
4 gallons a minute is the least that can be allowed, while 6, 8, or 10 
gallons per minute are better. . While the minimum is, as stated above, 
possibly less than a gallon a minute, it is not advisable to trust to 
less than 3 gallons per minute for each 100,000 eggs under the most 
favorable circumstances. 

If the water supply is drawn from a small brook or spring, it is neces- 
sary to measure the volume approximately, which is easily done, in the 
following manner: With a wide board 1 inch thick, having a smooth 
inch hole bored through the middle, a tight dam is made across the 
stream so that all the water will have to flow through the hole. If the 
water on the upper side rises just to the top of the hole, it indicates a 
volume of 2.3 gallons per minute; a rise of half an inch above the top 
of the hole indicates a volume of 3.5 gallons per minute; 2 inches rise, 5 
gallons per minute; 3 inches, 6 gallons per minute; inches, 8 gallons per 
minute ; 13 inches, 12 gallons per minute. If two 1-inch holes are bored, 
the same will, of course, indicate twice the volume. The volume of 
water flowing through holes of different sizes is in proportion to the 
squares of their diameters; thus a 2-inch hole permits the passage of 
four times as much as a 1-inch hole. A cylindrical tube whose length is 
three times its diameter will allow 29 per cent more water to pass than 
a hole of the same diameter through a thin plate or board. 

SITE. 

After a satisfactory supply of water is found a site for the hatching- 
house must be selected that affords facilities for creating a head of 
water to provide for the requisite fall into and through the troughs, 
security against inundation, security against too much freezing if in a 
cold climate, and, finally, general safety and accessibility. The fall 
required in the hatching-house can hardly be too great. The minimum 
is as low as 3 inches, but only under the most favorable circumstances 



MANUAL OF FISH-CULTURE. 37 

in other respects will this answer, and even then it is only admissible 
where there is an ample supply of aerated water and the troughs are 
very short and there is absolutely no danger of inundation; and this 
fall has the disadvantages of the impracticability of introducing any 
aerating apparatus and the necessity of having the troughs sunk below 
the floor of the hatching-house, which makes the work of attending the 
eggs and flsh very laborious. 

A fall of 1 foot will do fairly well if there is entire safety from inun- 
dation, as this will permit the troughs being placed on the floor, which 
is a better position than below it, though still an inconvenient one, 
and some of the simpler aerating devices can be introduced. Better is 
a fall of 3 feet, and far better a fall of 6 feet. The latter permits the 
placing of the lowest hatching-troughs 2 feet above the floor and leaves 
ample room for complete aeration. The necessities of the case are 
dependent largely upon the volume and character of the water, and 
if there is plenty of it, well aerated before reaching the hatching-house, 
there is no occasion, in a small establishment, of additional aeration in 
the house, and therefore no need of more than 3 feet fall. 

Inspection of the premises at time of floods will suggest the safe- 
guards necessary to provide against inundation. If located by a brook- 
side, the hatching-house should not obtrude too much on the channel, 
and below the house there should be an ample outlet for everything that 
may come. By clearing out and enlarging a natural watercourse much 
can often be done to improve an originally bad site. 

In a cold climate it is an excellent plan to have the hatching-house 
partly under ground, for greater protection against outside cold. When 
spring water is used there is rarely any trouble, even in a cool house, 
from the formation of ice in the troughs; but water from lake, river, or 
brook is, in the latitude of the northern tier of States, so cold in winter 
that if the air of the hatching-house is allowed to remain much below 
the freezing-point ice will form in the troughs and on the floor to such 
an extent as to be a serious annoyance, and if not watched will form 
in the hatching-troughs so deeply as to freeze the eggs and destroy 
them. Stoves are needed in such climates to warm the air enough 
for the comfort of the attendants; but the house should be so located 
and constructed that it may be left without a fire for weeks without 
any dangerous accumulation of ice, and if the site does not permit of 
building the house partly under ground the walls must be thoroughly 
constructed and banked well with earth, sawdust, or other material. 
In warmer climates no trouble will be experienced from this source. 

DAMS AND CONDUITS. 

The requisite head of water can often be had by throwing a dam 
across the stream and locating the hatching house close to it. The 
dam will form a small pond, which will serve the triple purpose of cool- 
ing, aerating, and cleansing the water. But uuless the character of 
the bed and banks of the stream are such as to preclude any danger 



38 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 

of undermining or washing out the ends of the dam, it is best not to 
undertake to raise a great head in this way. With any bottom except 
one of solid ledge there is always great danger, and to guard against 
it when the dam is more than 2 feet high may be very troublesome. If 
there is a scarcity of water, or if it is desirable, for aerating or other 
purposes, to secure a considerable fall, it is better to construct the dam 
at some distance above the hatching-house, on higher ground, where a 
very low dam will suffice to turn the water into a conduit which will 
lead it into the hatching-house at the desired height. 

A square conduit made of boards or planks, carefully jointed and 
nailed, is in nearly all cases perfectly satisfactory, and for an ordinary 
establishment a very small one will suffice. 

The volume of water that will flow through a pipe of a given form 
depends upon its size and the inclination at which it is laid. A straight 
cylindrical pipe, 1 inch in diameter, inclined 1 foot in 10, conveys about 
11 gallons of water per minute. The same pipe, with an inclination 
of 1 in 20, conveys 8 gallons per minute; with an inclination of 1 in 
100, it conveys 3£ gallons per minute; with an inclination of 1 in 1,000, 
it conveys 1 gallon per minute. A 2-inch pipe conveys about 5£ times 
as much water as an inch pipe; a 3-inch pipe nearly 15 times as much. 
A 1-inch pipe, with an inclination of 1 in 1,000, conveys water enough 
for hatching 25,000 eggs; with an inclination of 1 in 50, enough for 
100,000 eggs; with an inclination of 1 in 20, enough for nearly 200,000 
eggs. A square conduit conveys one-quarter more water than a cylin- 
drical pipe of the same diameter. If there are any angles or abrupt 
bends in the pipe, its capacity will be considerably reduced. It should 
be remembered that if the water completely fills the aqueduct it is 
entirely shut out from contact with the air during its passage, whereas 
if the pipe is larger than the water can fill, the remainder of the space 
will be occupied by air, of which the water, rushing down the incline, 
will absorb a considerable volume and be greatly improved. It is 
therefore much better to make the conduit twice or thrice the size 
demanded by the required volume of water. If the bottom and sides 
are rough, so as to break up the water, so much the better, and the 
wider the conduit is the more surface does the water present to the air. 

AERATION. 

The water which fishes breathe is but the medium for the conveyance 
of air, which is the real vivifying agent, without which fish and eggs 
will die, and with a scanty supply of which the proper development of 
the growing embryo is impossible. Water readily absorbs air when- 
ever it comes in contact with it, and the more intimate and the longer 
continued the contact the greater the volume it will absorb. The ample 
aeration of the water to be used in the hatching-house has already been 
mentioned as a desideratum of the first importance, and some of the 
devices by which it is to be secured have been alluded to. 

Water from either a brook or a river that has been torn into froth by 



MANUAL OF FLSH-CULTUEE. 39 

dashing down a steep bed has absorbed all the air that is needed in 10 
or 20 feet of hatching-trough, and demands no further attention on this 
score ; but if the water is taken from a lake, a spring, or a quiet brook 
it contains less air, which may be so reduced before it gets through the 
hatching-house as to be unable to do its proper work. It is therefore 
desirable to adopt all practicable means of reinforcing it. If the site 
of the hatching-house commands a fall of 5 feet or more, the object 
may be attained by contriving in the conduit outside the house, or in 
the hatching-troughs themselves, a series of miniature cascades. 

The broader and thinner the sheet of water the more thoroughly it is 
exposed to the air, and if, instead of being allowed to trickle down the 
face of a perpendicular board, it is carried off so that it must fall free 
through the air, both surfaces of the sheet are exposed and the effect 
doubled. If practicable, it is best to aerate in the conduit, which, as 
already suggested, may be made wide and open for that purpose. 

If aeration can not be effected outside the house it may be done 
inside by arranging two long troughs side by side, leveled carefully, 
so that the water is received in one of them and poured over into the 
other in a sheet the whole length of the trough. In the hatching- 
troughs themselves there is an opportunity for aeration either by 
making short troughs with a fall from one to another or by inclining the 
troughs and creating falls at regular distances by partitions or dams, 
each with its cascade, after the fashion already described. The only 
serious difficulty is encountered where the ground is very flat, so that 
the requisite fall can not be obtained, and in this case the best that 
can be done is to make a very large pool, several square rods at least, 
outside the house, and make all the conduits as wide as possible, so 
that the water shall flow in a wide and shallow stream. 

It will of course be borne in mind that the better the aeration the 
smaller the volume required to do a given work, and on the other hand 
it is equally true that the greater the volume the less aeration is 
necessary. When so large a volume as 6 gallons per minute for every 
100,000 eggs is at command, a comparatively small amount of aeration 
will answer. But, so far as known, the higher the degree of aeration 
the better the result, without limit, other things being equal, and it is 
therefore advised to make use of all the facilities existing for this 
purpose. 

FILTERING. 

Before the introduction of wire or glass trays for hatching fish eggs 
it was customary to lay them on gravel, and it was then absolutely 
necessary to filter all but the purest water. Even ordinary spring 
water deposits a very considerable sediment, which might accumulate 
upon the eggs to such an extent as to deprive them of a change of 
water and smother and destroy them. When, however, eggs are depos- 
ited on trays arranged for a circulation of water beneath, as well as over 
them, as described below, even though their upper side* are covered 
with sediment, they are clean and bright underneath and remain in 



40 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 

communication with the water beneath the tray, though of course the 
circulation of the water through the tray is not perfect. It is not, 
therefore, deemed necessary to introduce any considerable devices for 
filtering water which is naturally very pure, like lake and spring water 
when not subject to intermixture with surface water during rains; but 
where it is necessary to use water subject to constant or occasional 
turbidness some method of filtering is indispensable. 

In the majority of cases at least a portion of the water supply is 
obtained from an open brook, lake, or pond, and measures must be taken 
to get rid of the leaves and other coarse rubbish brought down by the 
stream or conduit. A great deal of such material is encountered in a 
stream at all seasons, but during fall and early winter it is especially 
abundant, and to secure entire safety from a stoppage of the water, and 
consequent loss, a screen on a generous scale must be provided. 

A description of the means adopted at this station for providing a 
temporary extra water service of several hundred gallons per minute, 
taken from Craig Brook, will serve as an illustration : A tank or vat, 
12 feet square and about 2 feet deep, is built in the bed of the brook 
with a tight dam of stones, gravel, loam, and leaves (these to stop 
small leaks) running ashore on either side, so that the entire volume of 
the brook passes over the tank. The bottom and sides are tight and 
strong, and both bottom and top are inclined about 6 inches down the 
stream. The cover is of spruce lumber sawed 1£ inches square, and 
nailed on in the direction of the current, with interstices open half an 
inch,- when in operation the water fills the tank and runs over the lower 
edge, which is raised enough to maintain a depth of several inches over 
nearly the whole tank. All leaves and other materials floating near the 
surface of the water are carried over, together with most rubbish which 
floats deep. At one of the lower corners of the tank, near the bottom, 
is a gate about 15 inches square, which is hung by hinges on its upper 
side. It opens inward, and is closed tightly by the pressure of the 
water ; but it can be easily opened by pushing with a pole from without, 
and then serves as a floodgate, whereby the tank may be thoroughly 
cleaned out. 

At the other lower corner is a conduit, 6 by 9 inches, which takes 
from this "leaf-screen" a supply of water not entirely free from rubbish, 
but so nearly so that a filter of moderate capacity can cope with what 
remains. A very useful adjunct would be a second horizontal screen 
of similar construction, through which the water that has passed down- 
ward through the first screen, as described, should next pass upward 
through the second; the first screen would remove floating debris, the 
second such as is heavier than water. 

The filter, situated about 70 feet from the leaf- screen, consists of a 
wooden flume, 12 feet long and 4 feet deep, divided lengthwise into three 
compartments, of which the central contains fine gravel held in place 
by a rack on either hand, of which the interstices are h inch wide and 
1J inches apart. The water from the leaf-screen is introduced into one 



MANUAL OF FISH-CULTURE. 



41 



of the* lateral compartments, and filters through the gravel into the 
opposite, compartment, from which it is taken by a plank aqueduct, 6 
by 6 inches, to the hatchery. Under the conditions described, and with 
a fall of about 1 foot from supply to discharge, this filter discharges 
over 300 gallons of water per minute into the aqueduct — water not abso- 
lutely pure, but sufficiently free from coarse dirt for the purpose. In 
many cases, where small quantities of water are used, it is customary to 
filter through flannel screens in the hatchery, and such filters do very 
good service. They can be introduced into the egg-troughs, or by 
running them lengthwise of a trough a very large volume of water can 
be filtered. 




Gravel Filter. 



h, a single long compartment for filtered water. 
i, j, racks to hold gravel in place. 
i is in 5 sections, movable, and can be taken out 
when gravel is to be renewed. 
k, I, sluices near bottom for cleaning out. 
m, wasteway. 
n, aqueduct to hatchery. 



a, conduit from brook. 
6, gate, swinging on pivot at c, to change 
direction of water. 

d, direct branch of conduit. 

e, reverse branch of conduit. 
/, /, etc., a single long compartment for unflltered 

water. 
g,g, etc., compartments occupied by gravel. 

A form of filter that has given good satisfaction at the Craig Brook 
station through five years of service consists in a series of graduated 
wire screens, through which the water passes upward, first through 
the coarser, and then through the finer screens, with provision for the 
reversal of the current for cleaning purposes. By reference to the 
above plan and section, it will be seen that the water is brought to 
the filter through a plank conduit, and is admitted to the filter through 
either of two gates that swing on hinges, one for the direct flow and 
the other for the reversal. The direct flow is first into a receiving 
chamber, which extends under the screens, then upward through the 
whole series and out at the top, overflowing into a catch-trough, from 
which it is distributed as desired. In cleansing, the supply gate is 
closed and the other one opened, and at the same time the sluice-gate 
at the bottom is opened ; the water then flows in full volume upon the 
screens and down through them, carrying all the intercepted debris 
into the lower chamber and out through the sluice-gate. 



42 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 

The wire filter illustrated has to pass some 500 gallons of water per 
minute, and has three screen-boxes, each of which carries 5 to 7 screens 
about 2 feet wide and 4 feet long; the meshes are from 2 inches down 
to £ inch square, and therefore intercept all coarse debris. 




Scale of feet. 



Wire Filter. 

It is but the work of a few moments to reverse the current and 
thoroughly cleanse the screens; when the autumn leaves are falling 
this must be doue several times a day, but at other seasons some days 



Report U. S. F. C. 1897. (To face page 43.) 



Plate 15. 




MANUAL OF FISH-CULTURE. 43 

elapse between the cleanings. The wire — even galvanized — rusts out 
in two or three years, and lately the coarser screens have been made 
of slender rods of oak, which will undoubtedly prove more durable. 

None of the filters described will intercept the finest sediment, and 
the water is finally passed through a capacious wooden reservoir, 30 
feet long, 8 feet wide, and 5£ feet deep, before it reaches the troughs. 
This answers the purpose well for the amount of water supplied by the 
filter last described (about 500 gallons per minute) and is regarded as 
well worth having, though even this will not insure limpidity in the 
water when the brook is swollen by rains. 

It may be mentioned that this reservoir is kept brimful at all times, 
so that all portions of the woodwork, except the railing surrounding it, 
are kept continuously wet and thus insured against decay for a very 
long period of years. 

CRAIG BROOK HATCHERY AND ITS EQUIPMENT. 

The Craig Brook hatchery derives its water supply from the brook, 
which has its source in Craig Pond, but which receives in the lower 
part of its course many copious springs. This spring water has some 
advantages, but possesses the serious disadvantage of such high tem- 
perature in winter as to unduly hasten the development of the eggs, 
causing them to hatch early and necessitating shipments of eggs in 
December. 

Accordingly, an aqueduct from a point on the brook above the springs 
brings to the hatchery a supply of cold water for winter use, in which 
eggs taken the first of November will not hatch until the following 
April. This is important, as, if the product of the season's hatching is 
to be liberated as fry, the late date of hatching will bring them to the 
feeding stage about the time when suitable food abounds in open waters, 
and if they are to be reared it is well to shorten up the sac stage and 
to have the early feeding stage fall at a date when the temperature of 
the water is rapidly rising, which will get the fish quickly through 
that most difficult of all stages of growth. 

The aqueduct is about 1,600 feet long, with a bore 4£ inches, and has 
a nearly uniform descent and total freedom from depressions, and is 
from end to end one single piece of cement concrete. It delivers to the 
hatchery about 100 gallons of water per minute, which is sufficient for 
the development of 4,000,000 eggs, and possibly many more. It was 
built in place around a slightly tapering core, which was drawn forward 
as fast as the mortar set, and it has now done good service for seven- 
teen years. By this means the temperature of the hatchery water is 
maintained 3° below that of the brook modified by the springs. During 
the five months from November 1, 1895, to April 1, 1896, the mean tem- 
perature in the hatchery was 36.65° F. 



44 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 

THE EGG HARVEST. 

The natural deposit of spawn by the Atlantic salmon in the rivers of 
the United States occurs during the months of October and November. 
In artificial operations at Dead Brook it has rarely been necessary to 
begin spawning before October 22, or to close later than November 15.* 

Dead Brook is commonly at a very low stage in August and Septem- 
ber, but it rarely fails that before October 20 there is a very material 
increase in volume. Whenever a sudden rise occurs, even in August 
or September, imprisoned salmon are at once excited to activity, and 
any aperture in the upper barrier sufficient to admit the body of a 
salmon is sure to lead to loss. As the breeding season approaches the 
sensitiveness of the fish to such influences increases, and a rise about 
October 20 is followed by a general movement of the salmon upstream 
in search of spawning-grounds. Advantage is taken of this circum- 
stance to entrap them at the upper barrier, where a small pound with 
a board floor and a barbed entrance, like that of a weir, is constructed a 
few clays in advance. The success of this trap depends on the stage of 
the water, and it is always the case that a portion of the fish fail to 
enter it, so that the final resort is to a seine, with which the recalcitrant 
salmon are swept out of pools where they are wont to lie. 

The fish are dipped from the trap or from the seine with soft bag-nets, 
such as are used in collecting them at the beginning of the season, 
assorted according to sex and condition, to facilitate manipulation, and 
placed in floating wooden pens, which are moored to the bank in front 
of the spawn-house. These pens are about 12 feet long and 4 feet wide, 
with grated sides and floors, affording sufficient circulation of water, 
and, although indispensable for the convenient manipulation of the fish, 
the confinement in such narrow quarters leads to considerable chafing 
of noses and tails, and if long continued affects the development of the 
sexual functions of the female unfavorably, retarding the maturity of 
the eggs and even affecting their quality. The capture of the fish 
from the brook is therefore delayed to the point of risking the deposit 
<>f some of the earliest eggs in the brook rather than the possible 
injuries in the pens. 

The spawn-taking operations begin as soon as any females are ready 
to yield their eggs. A scarcity of males in breeding condition has never 
yet occurred at this station at the beginning of the season, and hardly 
ever at its close. Among the earliest captures there are always a few 
unripe fish, but invariably by the last day of October all are ripe. 

The spawning-house consists of a single, plain room, with two doors. 
From one of the beams hangs a steelyard and a bag, in which salmon 
are weighed. At one end is a stove, in which a fire is built in very 
cold weather. At the other end is a graduated board, upon which the 

* In Canadian rivers the dates are but a little earlier. Thus at the Gaspe" hatchery, 
in the Province of Quebec, in 1894, the work of spawning began October 10 and closed 
November 2. 



Report U S. F. C. 1897. (To face page 45.) 



Plate 16. 




Ripe fish. 



Not ripe. 



EXAMINING FISH FOR STRIPPING. 




STRIPPING FEMALE SALMON. 



MANUAL OP FISH-CULTUKE. 45 

Ash are laid for measurement. At the front is a narrow table, on which 
the eggs are washed; and at the rear the entire side of the room is 
occupied by a series of shelves, on which the eggs are placed after 
fecundation and washiug. 

The spawn-taker, clad in waterproof clothing and wearing woolen 
mittens, sits on a stool or box, and on a box in front of him is a clean 
tin pan holding about 10 quarts, which has been rinsed and emptied 
but not wiped out. A female salmon is dipped up from one of the 
floating pens and brought to the operator, who seizes her by the tail 
with the right hand and holds her up, head downward. If unripe, the 
flsh is returned to the pens; if ripe, the spawn will be loose and soft 
and will run down toward the head, leaving the region of the vent 
loose and flabby, and the operator, retaining his hold of the tail with 
his right hand, places the head of the flsh under his left arm with the 
back uppermost, the head highest, and the vent immediately over the 
pan. At first the fish generally struggles violently and no spawn 
will flow; but as soon as she yields the eggs flow in a continuous 
stream, rattling sometimes with great force against the bottom of the 
pan. Shortly the flow slackens and must be encouraged and forced by 
pressing and stroking the abdomen with the left hand. It is better to 
use the face of the palm or the edge of the hand rather than pinch 
between the thumb and finger; the latter action, especially when work- 
ing down near the vent, is apt to rupture some of the minor blood 
vessels, with the result of internal bleeding, and it is better to leave 
some of the eggs behind to be taken another day than to run the risk 
of such ruptures. 

If the fish in hand is fully ripe, nine-tenths of the eggs are obtained 
at the first trial. • When the operation has apparently gone far enough 
for the first day, the fish is laid in the weighing bag, and as soon as the 
weight is recorded is stretched upon the measuring board, whence she 
is returned to the water, after a stay of 10 or 15 minutes in the air, 
which results in no permanent injury. Both the weight and length of 
the fish and the weight of the eggs are recorded, together with any thing- 
remarkable connected with fish or eggs. 

Large salmon endure transportation and confinement less success- 
fully than smaller ones, and the record therefore shows large numbers 
of salmon from 29 to 31 inches in length, weighing, including eggs, from 
9 to 12 pounds, and yielding 2£ to 3 pounds of spawn (6,000 to 8,700 
eggs), with now and then a fish 35 or 40 inches in length, yielding, in 
some cases, as many as 16,000 to 20,000 eggs. 

As soon as the spawn of a single female is taken, a male is brought 
to the spawn-taker and the milt expressed upon the eggs. The pan is 
then swayed and shaken violently until the milt becomes well dis- 
tributed and in contact with every egg. If the quantity of spawn 
exceeds 3 pounds it is divided and fecundated in two pans instead of 
one, as it is difficult to secure a good result if the eggs lie in too great 



46 REPORT OF COMMISSIONER OP PISH AND FISHERIES. 

masses. The eggs are passed over to the washer, who repeats the 
swaying and the shaking, and, having weighed them, pours in a small 
quantity of water and goes through the mixing process for a third 
time. After this the eggs are immediately washed by pouring in an 
abundance of water and turning it off, and repeating the operation 
until the water appears quite clear, when the eggs are placed on the 
shelves in the rear of the apartment, to await the process of swelling. 
When the egg first comes from the fish it has a soft and velvety feeling 
to the hand, and the outer shell lies loose and slack against the yolk. 
The presence of water excites the shell to action ; its pores absorb water 
with such force that any foreign object coming in contact is sucked 
against it, and in consequence of this suction the eggs stick to the pan 
and to each other. In the course of 20 or 30 minutes this process is 
completed, the shell is swollen to its utmost extent and is firm to the 
touch, the space between the shell and the yolk is now filled with water, 
and adhesion to outer objects ceases. 

The eggs can now be laid upon trays and carried to the hatchery. 
No serious harm would ensue if the eggs should be disturbed during 
the process of swelling, but it is better not to spread them upon trays 
until they have attained full size and ceased to adhere to each other, 
and they are left on the shelves until the spawning for the day is over, 
when all are carried to the hatchery together. After the absorption of 
water the eggs must be handled very gently, as they are now suscep- 
tible to injury from sudden shocks, such as might ensue from pouring 
them from pan to pan, or setting the pan containing them down roughly 
upon a wooden table, and to guard against such injuries the tables and 
shelves are covered with old nets or other soft material. 

CONDITIONS AFFECTING FECUNDATION OF EGGS. 

While the spawn of a salmon is, with very rare exceptions, in normal 
and healthy condition and capable of fecundation within the limits of 
the spawning season, occasionally a fish is found whose eggs are in 
some way defective. Sometimes they are developed unevenly, the 
ovaries containing eggs in various stages of growth, some mature and 
some rudimentary; sometimes all the eggs of a fish are abnormally 
small, and sometimes all have defects which render them incapable of 
fecundation. But among the thousands that have been manipulated 
at the station not 1 in 300 has had defects involving as many as 20 
per cent of her eggs, and in the spawn deemed of normal quality there 
can hardly be more than 1 defective egg in 400. Among the males no 
instance has occurred where there was reason to suspect the milt of 
being of defective quality if secured from a living fish. 

In 1872 experiments were made bearing on the duration of the 
capacity for fecundation of the eggs with interesting results. From 
eight lots of eggs taken from dead fish, the rates of impregnation ranged 
from 92£ per cent down to zero. From a fish that had been dead 2 



MANUAL OF FISH-CULTURE. 47 

hours 4,400 eggs were obtained, of which only 58£ per cent were capable 
of fecundation. In one instance eggs taken from a dead fish and kept 
until the morrow before milting remained so far in normal condition 
that 12£ per cent were fecundated. In another case 400 eggs from a 
fish that bad been dead 15 hours failed totally ; and the same result 
was obtained with 2,200 eggs taken from four specimens killed two days 
before. 

The same experiments afford evidence as to the result of keeping eggs 
for various periods of time after they are taken from the tish, and 
eggs exposed to the air and guarded against contact with water appear 
to keep better than in the organs of a dead fish. Thus, 200 eggs were 
kept in a pan without water for 12 hours after they were taken from 
the fish, and the application of milt then resulted in the impregnation 
of 90 per cent; of 200 eggs kept in the same way for 30 hours and then 
treated with fresh milt, 87£ per cent were impregnated; and of 100 eggs 
kept 4 days and then treated with fresh milt, 12 were impregnated. 

Milt taken from a living male and kept in an open dish for several 
hours retains its powers fully, but experiments with milt from dead fish 
have given almost wholly negative results. Numerous experiments 
show that if eggs are merely covered by water, without effort to secure 
intermixture or the washing off of the mucus that envelops them when 
pressed from the organs of the mother fish, their susceptibility to fecun- 
dation may not be seriously affected by immersion 5 or G minutes; but 
if the eggs are stirred, so as to facilitate the washing off of the mucus 
and the access of pure water, immersion for 1 or 2 minutes may pre- 
vent impregnation. 

When thoroughly diluted with water the milt speedily loses its 
power, the effect being very marked at the end of 30 seconds; diluted 
with the mucus that accompanies the egg, it will remain effective for a 
long period. Where water has been carefully excluded, milt has been 
used successfully after the lapse of 12 hours with landlocked salmon, 
and this would probably hold with eggs of all kinds of salmon and 
trout. This property of the mixed mucus and milt has been utilized 
in impregnating masses of eggs when there is a scarcity of males, as 
sometimes occurs toward the close of the spawning season. In strain- 
ing the mixed mucus and milt from the pan of eggs, the lower strata, 
which are richer in milt than the upper, should be especially secured 
and the mixture kept in a convenient receptacle. The upper strata of 
the mixture should not be used, as the milt settles to the bottom. 
Fresh milt should always be preferred when obtainable. 

The eggs are washed as soon as the milt is thoroughly diffused among 
them, and this can hardly be done too speedily for the milt to act. A 
careful record of certain lots of eggs that were washed in special haste 
for experimental purposes shows that they were as well impregnated 
as those exposed to the action of the milt for a considerable period. 
Prolonged exposure to the milt has been found to affect the health and 
development of the embryo unfavorably. 



48 REPOKT OF COMMISSIONER OF FISH AND FISHERIES. 

TRANSFER OF EGGS TO THE HATCHERY AND THEIR CARE. 

From Dead Brook the eggs are transferred to the hatchery at Craig 
Brook station, about 2 miles, and spread on trays in the spawning- 
house. The trays are placed in frames, inclosed in boxes which are 
padded within to guard against concussion. In spite of all precautions 
some of the eggs are occasionally killed, though the trays are placed in 
pans of water and the eggs poured from the spawning-pans with the 
greatest care. The frames or " stacks " containing the eggs are placed 
at once in the troughs where they are to be developed. 

The trays are 12^ inches square, and constructed by attaching iron 
wire-cloth to light wooden rims with blocks at the corners, so that when 
piled up, one above another, there are narrow interstices on all four 
sides, through which water circulates freely. The rims of the trays 
are very slender, in order that they may never have buoyancy enough 
to float, which would necessitate some means of holding them down and 
increase the trouble attending their manipulation. Southern poplar 
(whitewood) is commonly used, and a rim J inch wide and | inch deep 
answers the purpose well, provided the wire be not very light. The 
corner pieces are £ inch thick, and give the interstices just enough 
width to provide an ample circulation of water, but not enough to 
allow the escape of salmon eggs, which are nearly | inch in diameter. 
Rusting is prevented by varnishing the wire-cloth with several coats of 
asphaltum varnish, which works better if made very thin by the use of 
a large proportion of spirits of turpentine. The same varnish gives a 
clean and glossy surface to submerged woodwork, and the varnishing 
is extended to the rims of the. trays, the "stack-pans," and the interior 
surfaces of the troughs themselves. Material subject to rust should be 
used only with great caution. Wire or other metallic forms galvanized 
with zinc vary in quality. Total loss of eggs has been known to result 
from the use of galvanized'wire-cloth when unvarnished. Careful 
experiment should precede the use of any particular brand. Tinned 
wire cloth is better, but whether enough so to warrant the extra 
expense is a question. 

In developing eggs, in order to economize room, the trays are piled 
up 10 or 20 deep in frames that conhne them only at the corners and do 
not hinder the free passage of water horizontally through the " stack." 
About 2,000 Atlantic salmon eggs are placed on a single tray, and a 
trough of the ordinary length, 10£ feet, therefore carries 140,000 to 
280,000 eggs, with suitable free space at either end. It is therefore an 
exceedingly compact apparatus and has the further advantage that it 
can be used in a very plain trough which can, with a few minutes' work, 
be transformed into a rearing-trough for young fish. For 10-tray stacks 
the trough is made of pine boards, 12| inches wide and 9 inches deep 
inside, and is set up level, with the top about 30 inches from the floor of 
the room. 



MANUAL OF FISH-CULTURE. 



49 



The water is fed into one end through a wooden or rubber tube 
guarded by a wire screen, and is regulated by a simple swinging 
gate. The outlet is either over a wooden dam or through a hollow 
plug, either of which determines the height of the water in the trough 
which is always maintained just at the top of the covering tray or an 
eighth of an inch above it. 

Fig.l. 





Scale of feet. 




Trough Arranged for Egge. 
Fig. 1 , plan. Fig. 2, longitudinal section. 



a, supply-trough 

b, screen. 

d, supply -pipe. 
/, egg-trough. 



j, down- spout. 

r, cleats. 

s, stacks of egg-trays. 

?, waste-pipe. 



u, screen. 

v, outlet. 

iv, wooden dam. 

x, water surface. 



For the regular picking and cleaning, and for other examinations, the 
stacks are removed from the trough to a table, where the trays can be 
taken out one by one, set over into an empty frame, and returned to 
the trough. This can be performed with ordinary caution at any stage 
of the development of the embryo, without doing the slightest injury, 
and after the delicate stage is passed the trays and their burden of 
eggs can be washed at the same time in a pan of water. 

WINTER CARE OF EGGS. 

The eggs pass the winter in the stacks. They are regularly picked 
over and the dead ones removed once or twice a week — twice during the 
hist few weeks, on account of the comparatively high temperature then 
prevailing and the consequent rapid development of decay and growth 
of fungus. It depends, to a considerable extent, on the water tempera- 
ture; the water at the beginning of the spawning season varies from 
50° to 55° F., and maintains a mean of 43° to 45° F. during the month 
of November. 

The color of a good egg, or of an unimpregnated egg that stdl retains 
its vitality, is a translucent salmon pink, with some variations in shade. 

F. C. E. 1897 1 



50 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 

It is possible, by placing it in a favorable light, to get a fairly good 
interior view, including the detailed anatomy of the embryo. When 
the egg dies it turns chalky white, becomes wholly opaque, and in a few 
days, depending on the temperature, decay sets in, and sometimes a 
white water- mold or fungus begins to grow upon it. The mere decay 
of the egg would foul the water, thereby injuring the neighboring eggs, 
and the fungus established on the dead eggs may spread to the living 
ones. It is therefore essential that the white eggs be removed before 
they have time to do any injury. 

For egg-picking a homemade pair of tweezers, about 6 inches long, is 
used, made of any convenient wood and tipped with a pair of wire 
loops of a size to conveniently grasp the egg. The operator lifts the 
stack of trays carefully from the trough and, to save dripping, carries 
it on a wooden waiter to a well-lighted table of convenient height, on 
which stands an oblong pan, 14 by 18 inches, holding about an inch of 
water. 

The stack of eggs to be picked is placed at one end of the pan and 
at the other end is an empty stack-frame. The trays are examined one 
by one, dipped in the pan of water', picked (or cleaned by agitation 
when the eggs are in condition to endure the disturbance), and placed 
in the empty frame. The air of the room is kept at a low temperature 
during this process, and the water in the pan is often changed. 

The eggs when first impregnated are very sensitive to rude shocks and 
are handled with great care. Within a few hours the germ begins to 
develop; in 10 days, at a temperature of about 40° F., the germ-disk 
appears as a ring of color on the upper side of the yolk. At this date 
the unimpregnated egg presents the same appearance and does not 
change much until its death, however long that may be deferred. In 
the impregnated egg, however, the germ-disk continually enlarges upon 
the surface of the yolk ; the ring of color that marks its edge advances 
before it, passing quite round the yolk, and closing up on the posterior 
side. 

As early as the thirteenth day the difference between the impregnated 
and unimpregnated egg is quite plain to the unaided eye after a very 
little experience, and three or four days later the good egg is marked 
by a distinct line of color passing around the very middle of the yolk, 
a phenomenon never appearing in an unimpregnated egg. During 
this stage, while the embryonic disk is spreading around the yolk, 
the egg grows constantly more and more delicate, and liable to rupture 
of its tissues and consequent death on very slight disturbance; but 
later the tissues grow stronger, and when, about the thirty-fifth or 
fortieth day, the eyes of the embryo have assumed enough color to 
appear as two dark dots, the egg has attained hardiness enough to 
endure rougher handling. Thenceforward, until the near approach of 
the time for hatching, the work consists simply in picking out the dead 
ones, occasionally rinsing out the sediment, and sometimes removing 
the unimpregnated eggs. 



Report U. S. F. C. 1897. (To face page 51 ) 



Plate 17. 




PICKING OUT DEAD EGGS. 



PACKING SALMON EGGS. 




HANDLING EGG-TRAYS. 



MANUAL OF FISH-CULTURE. 51 

The latter procedure is attended to for the entire stock of eggs, but 
is of special importance in case of those that are to be transported. It 
may be performed any time after the good eggs become hardy — that is, 
after the eyes become black — but becomes easier late in the season. The 
unimpregnated eggs, which were at first fully equal in hardiness to the 
impregnated, lose in that respect as time passes, and finally are readily 
killed and turned white by a shock which does no injury to the impreg- 
nated eggs. When this time has arrived, the eggs are turned from the 
trays into spawning-pans with a moderate quantity of water, and 
poured from pan to pan back and forth a dozen times, each time falling 
a foot or more, and striking the bottom of the pan with considerable 
force, giving each egg a severe shock. They are then returned to the 
trays and troughs and as soon as convenient are picked, and if the 
operation has been thorough almost every unimpregnated egg has 
turned white and is picked out, while the eggs in which the embryos 
are developing have not suffered at all. 

PACKING AND TRANSPORTING. ' 

Eggs may be safely transported as soon as the eyes have become 
thoroughly colored, and until within a few weeks (five or six in cold 
weather) of the date for hatching. In shipments made too late the shells 
burst on the way and the embryos perish. The method of packing eggs 
at Craig Brook is to put them in layers alternating with wet sphagnum 
moss in shallow wooden boxes, placed in cases of a size to afford on 
all sides of the inner package a space of 2£ or 3 inches, which is filled 
with some light, porous material that will form a good nonconductor 
of heat. 

The eggs are thrown from hatching- trays into a large rectangular 
pan, from which they are poured with water into tin measures which 
hold 2,500 each. A thin layer of moss is placed in the bottom of a 
packing-box. A little fine snow is sifted upon the moss, and on this is 
spread a piece of mosquito netting that has been soaked and rinsed in 
clean water. A measure of eggs is now poured on and spread out and 
covered by folding over the edges of the netting, which now completely 
envelops them. Next a layer of moss is spread, followed by snow, 
netting, and eggs, as before, and the series is repeated until the box is 
full. The moss must be sufficiently wet, so that with the melting of the 
snow it shall have all the moisture it will hold, and no more, as it is 
very desirable to avoid the wetting of the outer packing. If the 
moss is too dry, the eggs may dry to the extent of becoming indented, 
and the same result may come from crowding the moss in too hard on 
the eggs, though it should be pressed in so tightly that the eggs will 
not slide out of place if the case is turned for a moment on its side. 

The temperature of the packing-room is below 50° F., and packing 
materials are kept in a place which is cool, yet not much below the 
freezing-point. Salmon eggs packed as above commonly go a three 
days' journey without completely melting the snow that was sprinkled 



52 



REPORT OF COMMISSIONER OF FISH AND FISHERIES. 



under the eggs, and on several occasions eggs of landlocked salmon 
have been carried across the Atlantic in prime condition, without 
repacking or special attention. 

The packing-boxes are made of thin pine or fir, 12 inches wide and 15 
inches long — |-inch thick boards being used for the end pieces and 
J-inch for the other parts — and hold in a single layer, without crowding, 
2,500 eggs. The deepest are 3i inches deep and take four layers, or 
10,000 eggs, in a box. To make up a shipment of 40,000 eggs, four boxes 
are piled up and secured together by tacking strips of wood against 
the ends, with a cover on the upper box, and this package placed in 
the case. For a shipment of 80,000, two of the 40,000 packages are put 
side by side in a larger case, and the proportions selected for the inner 
boxes are such that the case required is of convenient form. 



2S5S®SSg§tea&SS§ 













'TJVj 777,/ r^c^^^.^U^'(-%. ' LV. , - ' i--L'."L ^ : ^^ : 



,^199^000 0690000 









^>^a^^gS 









//?/7))///7//'/7//777////7/7/777/7//7/ 777/ ////// ////// //////> 



Longitudinal section of a case of Atlantic Salmon eggs. 

Different mosses can be used for packing, but none are so good as 
the sphagnous moss that can be found in swamps and bogs in most 
regions of high latitude or considerable elevation. Fresh moss is 
preferable for a bed for the eggs, though dead, dry moss may be moist- 
ened and used with good results. 

The moss is gathered in August or September, dried on the ground, 
and stored in sacks or in bulk until wanted. It retains its freshness 
through the following winter, not heating like most organic materials. 
It is exceedingly light, and the best nonconductor known, with the 
possible exception of asbestos. It is used dry in the outer packing 
mainly to save weight, but when protection against freezing is all that 
is sought, wet moss is better, as frost penetrates wet moss more slowly 
than dry. When moss can not be had, there are many substitutes 
which may be used for the protective envelope, such as dry forest 
leaves, chaff from a haymow, chopped hay, or even crumpled papery 
but the latter should not be allowed to become wet. 



MANUAL OF FISH-CULTURE. 53 



HATCHING. 



As the time for hatching draws near, the eggs are placed on trays 
provided with legs or some other support to keep them up from the 
bottom of the trough. Brass nails driven into the under sides of the 
tray rims are good temporary legs, and after the hatching is over they 
are readily removed and the necessity of a special set of trays for 
hatching is avoided. When there are plenty of troughs, these trays 
stand singly on the bottom of the trough, but when it is necessary to 
economize room two or even three are disposed one above another. 
When no necessity exists for economy of space, 4,000 eggs are allowed 
a whole trough, which is at the rate of 400 to the square foot; 2,000 
or even 5,000 to the square foot may be carried through hatching and 
the entire sac stage, but the latter number involves risky crowding. 

The hatching is sometimes expedited by giving eggs that are just at 
the hatching point a decided shock, similar to that given at an earlier 
date to kill the unimpregnated ones ; also by the temporary stoppage 
of the water supply. But at Craig Brook it is the custom to lay the eggs 
out in good season and allow them unlimited time in which to hatch, 
sometimes a week, sometimes two weeks. The earliest lots commonly 
hatch the latter part of March, and it is not often that any remain 
unhatehed after April 20. The mean duration of the egg stage is 
therefore about 157 days, during which the mean temperature of the 
water has been about 37° P. While hatching is progressing, the outlet 
screens are closely watched to keep the empty shells from clogging 
them up; for when a considerable part of the screen is clogged the 
force of the current through the open spaces is greatly increased, and 
the soft and yielding sacs of the fish are liable to be drawn through 
the meshes. 

THE SAC STAGE. 

When the shell breaks, though it has been coiled up in a space less 
than ^ inch in diameter, the trunk of the newly hatched salmon at once 
straightens out to a length of about § inch. The yolk, scarcely dimin- 
ished from its original size, hangs beneath and constitutes the greater 
part of the bulk of the fish. The young salmon is for a while more 
unwieldly than a tadpole. When frightened he sculls about with great 
energy, but makes slow progress and is fain to lie on his side on the 
bottom of the trough or crowd with his companions into a corner. The 
sac is a store of nutriment, which is gradually absorbed into the other 
parts of the fish ; and so long as it lasts the young salmon will not eat. 
The interval between hatching and total absorption of the sac varies 
with the temperature, the mean at Craig Brook in April and May being 
about six weeks. 

As time passes the embryo fish grows more and more to resemble the 
adult, his body acquires strength, and his fins assume form and become 
more effective as organs of propulsion. At last his digestive system 



54 



REPORT OF COMMISSIONER OF FISH AND FISHERIES. 



assumes its functions and rouses the desire for food. Until this time, 
intent only on hiding, the fry have clung obstinately to the bottom and 
to the dark corners, but now they scatter about through the water, 
with heads upstream watching for prey. This indicates that they 
must be fed. During this period of his growth it is simply necessary 
to see that the young fish has plenty of water, that there is no hole or 
crevice into which he can be drawn by the current, and that he is pro- 
tected from enemies, such as large fishes, minks, rats, kingfishers, and 
herons. If not in a house, well-fitting covers must be provided to the 
troughs and impassable screens command both ends. The screens are 
of fine wire-cloth, 12 or 14 meshes to the linear inch, and present a sur- 
face of 14 square inches to each gallon of water passing through them 
each minute. Thus, if there are 4 gallons of water passing through the 
trough each minute the portion of the screen beneath the surface of the 
water must measure as much as 56 square inches, and if the screen is 
12 inches wide the water must be 4f inches deep on the screen. 




Atlantic Salmon, recently hatched. 



REARING. 

The leading feature of the work of the station is the rearing of fry to 
the age of six or eight months. The fishes reared are mainly Atlantic 
salmon, but landlocked salmon, American brook trout, European brook 
trout, rainbow trout, steelhead trout, American lake trout, Swiss lake 
trout, Scotch sea trout, and saibling have also been handled. The fish 
are fed wholly on artificial food from about June 1 till October or 
November, when they are mostly liberated. To a limited extent they 
are kept in artificial ponds, but troughs of the same form and dimen- 
sions as those already described for use in developing the eggs and in 
hatching have given satisfactory results and have been adopted for the 
most part. Each trough is provided with a changeable outlet screen 
and below the screen discharges the water through a hole in the bottom, 
into which is fitted a hollow plug, the height of which determines the 
depth of water in the trough. The hollow plug plays an important part 
in the daily cleaning of the trough, which will be referred to further on. 

The use of the troughs in the open air, which, in the absence of com- 
modious buildings, is a necessity, compels the constant use of covers -to 
keep out vermin ; and wooden covers in pairs, running the whole length 



MANUAL OF FISH-CULTURE. 



55 



of the trough, hinged to its sides, and, when closed, assuming the form 
of a roof at an angle of 45°, were finally adopted. These covers are 
made of thin boards, f inch thick, sawed in narrow pieces, which are 
put together so as to leave in each corner two cracks open ^ inch wide 
for the admission of light when the covers are closed. When open they 
may be fixed in an upright position, thus increasing the height of the 
sides and guarding against the loss of fish by jumping out. 




Tig.1 



fc* 




J " 



Troughs arranged for Rearing. 
Fig. 1, plan. Fig. 2, longitudinal section. Fig. 3, cross-section near foot of trough. Fig. 4, inlet, 



"with rocking gate. Fig. 5, elevation of lower end. 

a, supply-trough. 
6, screen. 

c, rocking gate. 

d, supply-pipe. 

■ e, water-"board (to spread the water and throw it down) 
/, fish-trough. 

<f, gripe, to prevent spreading of sides. 
h, outlet screen. 



i, hollow outlet plug. 
j, down-spout. 
h, supports. 
I, cover. 
m, cover open (hanging). 
n, cover open (upright). 
p, cover closed. 
q, end boards (closing aperture). 



Water is furnished through rubber or wooden pipes § inch in diame- 
ter, and the bore of the hollow plug at the outlet is 1^ inch or larger. 
The inflow is regulated by an oscillating or rocking gate, which is set 
to admit the desired volume of water. The trough is set with the 
upper end an inch or two higher than the other, to facilitate cleaning 
out, and the water is kept during the summer about 4 inches deep at 
the lower end. 



56 



REPORT OF COMMISSIONER OF FISH AND FISHERIES. 



The troughs are supported by a suitable framework at a convenient 
height from the ground and arranged in pairs with their heads against 
a long feed-trough, constructed of pine boards and perforated on the 
side by the feed-pipes, over each of which is a capacious screen to pre- 
vent clogging by leaves or other floating debris. A frame 6 by 12 
inches, covered on its outer side^by wire-cloth of f inch square mesh, 
answers the purpose of a screen so well that water from an ordinary 
brook can be admitted to the feed-trough without previous filtering or 
screening and with little or no danger of a stoppage of water in any 
of the fish-troughs. Such screens over the feed-pipes might be made 
the sole dependence, were it not that the labor attending their cleaning 
would be greater than that required by a separate filter or screen. 



Conduit, to lower levet. 



n 



Fish, trozuik. 



^= 



Scale of feefc. 



U 

Stand of Troughs for Rearing Atlantic Salmon. 

The system represented here by 12 troughs in two series may be 
extended to many hundreds of troughs in four (or more) series, each 
series on a different level and receiving water from the series next 
above, the fall from one to another being about 4 feet. In the drawing 
the series of 6 troughs on the left is supplied with water directly from 
the upper "feed-trough" (i. e., supply-trough), and they discharge into 
a catch-trough, from which the water is carried to the supply-trough 
("feed-trough") of the lower level. If the aqueduct supplies more 
water than the upper series of troughs can use, the surplus passes by 
way of the "overflow" directly to the catch-trough and thence to the 
supply-trough of the second series. With a fall of 4 feet, the catch- 
trough and the conduits that lead from it are below the walks which 
give access to the troughs on both sides and at the lower end. 

The number of fish assigned to a single trough is ordinarily 2,000, 
and the volume of water giveD them is commonly 5 gallons per minute. 
Generally the water is used but once in troughs and is discharged 



MANUAL OF FISH-CULTURE. 57 

into conduits leading- to ponds where larger fish are kept ; but a stand of 
100 troughs has lately been set up with the design of using all the 
water twice; and for many years there has been one system of 52 
troughs, arranged in four series, which use in succession the same 
water, the young salmon thriving quite as well in the fourth series as 
in the first. 

On one occasion a few of them were maintained for several weeks in 
the warmer water of a neighboring brook, where a trough was set up 
and stocked with 100 young salmon taken from one of the troughs at 
the station July 30. The temperatures observed between 1 and 4 p. m. 
in the fish-trough on successive days from July 30 to August 14, not 
including August 1 or 10, were as follows: 79°, 75°, 77°, 79°, 82°, 82°, 
78°, 76°, 76°, 76°, 74°, 74°, 74°, 74°, F. 

The fish were fed the same as the lot out of which they were taken, 
except that they received food only once a day instead of twice, and 
were returned to the station October 7 without a single loss during the 
experiment. Moreover, they were all weighed October 10 and found 
to average 100.6 grains, while those of the original lot that had remained 
at the station, with a temperature between 50° and 71° F., averaged 
only 56.1 grains. While the greatly increased weight of the fish kept 
in the stream was owing in part to more space, as the 100 had as large 
a trough as 1,505 at the station, the higher temperature was undoubt- 
edly one of the factors that contributed to the gain in weight, and it is 
at least plainly shown that the warm water was not unhealthful. 

Though small ponds, excavated by the former proprietor, were in 
existence at the station and used to some extent for rearing young fish 
in their first summer as far back as 1888, and older fish have been kept 
in small ponds each season since that, it was not until 1896 that enough 
pond work was done to furnish data of importance. 

The ponds for rearing Atlantic salmon are among the series known 
as the "south ponds," occupying a smooth piece of ground sloping 
toward Alamoosook Lake at a grade of 1 in 8. Formerly it was mostly a 
swale, watered by a copious spring at its head. This series comprises 19 
ponds of rectangular form, about 50 to 90 feet long and 15 feet wide, with 
a depth of 2 or 3 feet. The water supply of those used for Atlantic sal- 
mon is derived from Craig Brook by an aqueduct tapping it at a point 
where two parts of Craig Pond water are mingled with one part spring 
water, being substantially the same as the water supplying the most 
of the rearing-troughs. From 5,000 to 10,000 fish that have been fed in 
troughs during the early pare of the feeding season are placed in each 
pond, and for the remainder of the season are fed the same food that is 
given to the fish left in the troughs; and the results indicate that the 
stock of fish might be safely increased. 

While the greater part of the salmon reared at Craig Brook are 
liberated in October, when about seven months old, in 1891-92 about 
16,000 were carried through the winter, most of them in tanks sunk 
in the ground, and nearly as many have been wintered some other 



58 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 

seasons. Fish may also be kept all winter in troughs in the open air 
by occasionally spreading blankets over them in exceptionally cold 
weather, and keeping the conduits carefully covered. 

The fish surviving the summer season are generally counted and 
weighed in October, in the following manner : A large number of them 
are dipped up from a trough in a small dip net made of cheese-cloth, 
and from this, while it is hanging in the water in such a manner that 
the fish can not escape, they are dipped out a few at a time, in a small 
dipper or cup, counted, and placed in another bag net until a sufficient 
number (generally 200) are counted, when they are lifted out of the 
water, held a moment in the air to drain, and all turned quickly into 
a pail of water which has previously been weighed. With care no 
appreciable amount of water goes with the fish, and the increase in the 
reading indicates their weight with a fair approach to accuracy, and 
with care and celerity of action it is quite safe for the fish. 

The size attained by the fish varies greatly, being affected by the 
water, the space allowed, the feed, and perhaps by hereditary influences; 
but when seven months old a trough-reared salmon is generally from 
2h to 3 inches long and weighs from 35 to 100 grains, the maximum being 
about 130 grains and the minimum as low as 7 grains, the general 
mean for 1896 being 45.8 grains. Salmon reared in ponds have been far 
more thrifty, their general average in 1896 being 101 grains.* The 
losses in ponds from July to October were rather heavy, being 11.7 per 
cent, owing to depredations of frogs, birds, and cannibal fish. The 
losses in the troughs during the entire season were 9.1 per cent, but 
most of these were in the early stages of fryhood. After July losses in 
troughs are always very light. 

MATERIALS FOR FISH FOOD. 

At Craig Brook station there have been used butchers' offal, flesh of 
horses and other domestic animals, fresh fish, and maggots. Experi- 
ments have also been made with pickled fish, blood, fresh-water 
mussels, mosquito larvse, miscellaneous aquatic animals of minute size, 

*A very interesting comparison between the results of rearing in troughs and 
ponds is afforded by the record of two lots of steelhead trout during the season of 
1896. All the fry of this species that were devoted to rearing were fed in troughs 
until July 22, when some of them were transferred to a pond which has an area of 
about 1,100 square feet and another lot was kept in a trough. The two lots were fed 
exactly alike, about one-sixth of their nutriment being liv maggots, and five-sixths 
chopped meat, liver, and other butchers' offal. November 7, the lot in the trough 
was overhauled, and the 762 survivors found to weigh 10 pounds 4 ounces, or an 
average of 94 grains. Three days later the pond fish were seined out and the 7,398 
survivors found to weigh 235 pounds 10 ounces, an average of 223 grains. It is not 
believed that natural food occurring in the pond contributed much to this result, and 
it would appear that the controlling factor in the case was the space afforded the 
fish. Leaving out of the account the difference in depth, in the pond there were less 
than 7 fish to each square foot of area, while in the trough, which had an area of 
about 11 square feet, there were to each square foot 69 fish. A similar illustration 
was furnished by 41 rainbow trout of the hatching of 1896 that got astray in one of 
the ponds and were taken out November 11, weighing 480 grains each. Those 
of t'he same age, reared in troughs, attained during the season only a weight of 136£ 
grains each. 



MANUAL OP FISH-CULTURE. 59 

flour, and middlings. The butchers' offal comprises livers, hearts, and 
lights, which are collected from the slaughter-houses twice or thrice 
weekly, and preserved in refrigerators until used. 

The flesh of old and worn-out horses has been used each year since 
1892 in the same way as the butcher's offal, with very satisfactory 
results; the parts that could be chopped readily have been fed direct 
to the fish so far as needed, and other parts have been used in the 
rearing of maggots. 

Next to chopped meat maggots have constituted the most important 
article of food, and their systematic production has received much 
attention. A rough wooden building has been erected for this branch 
of the work, and one man is constantly employed about it during the 
summer and early autumn months. The maggots thus far used are 
exclusively flesh-eaters, mainly those of two undetermined species of 
flies; the first and most important being a small, smooth, shining green 
or bluish-green fly, occurring in early summer and remaining in some- 
what diminished numbers until October; and the other a large, rough, 
steel-blue fly that comes later and in autumn becomes the predomi- 
nating species, having such hardiness as to continue the reproduction 
of its kind long after the occurrence of frosts sufficiently severe to 
freeze the ground. 

To obtain maggots meat is exposed in a sheltered location accessible 
to flies during the day. When well stocked with the spawn of the flies 
it is placed in boxes, which are set away in the " fly-house " to develop; 
when fully grown, the maggots are taken out and fed at once to the fish. 
Stale meat, parts of the butchers' offal and of the horse carcasses not 
adapted to chopping; fish, fresh, dried, or pickled; fish pomace from 
herring-oil works, and any animal refuse that comes to hand, are used 
to entice the flies and afford nourishment for the maggots. Fresh fish, 
when not too watery or oily, like alewives and herring, is very attract- 
ive to the flies, and in proper condition may serve as well as fresh meat. 
Fish dried without salt or smoke and moistened before using is, when 
free from oil, a superior article. Its preparation presents some diffi- 
culties, but in winter it is easily effected by impaling whole fishes on 
sticks and hanging them up under a roof where they will be protected 
from rain without hindering the circulation of the air; in this way 
many flounders and other refuse fish from the smelt fisheries have been 
dried. 

It is usually necessary to expose meat but a single day to obtain suf- 
ficient fly spawn; the larvae are hatched and active the next day, except 
in cool weather, and they attain their full growth in two or three days. 
To separate them from the remnants of food the meat bearing the fly 
spawn is placed on a layer of loose hay or straw in a box which has a 
wire-cloth bottom, and which stands inside a slightly larger box with a 
tight wooden bottom. When full grown, the maggots work their way 
down through the hay into the lower box, where they are found nearly 
free from dirt. 



60 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 

When young salmon or trout first begin to feed they are quite unable 
to swallow full-grown maggots, and small ones are obtained for them by 
putting a large quantity of fly spawn with a small quantity of meat, 
the result being that the maggots soon begin to crowd each other and 
the surplus is worked off into the lower box before attaining great size. 
No attempt is, however, made to induce the young fish to swallow even 
the smallest maggots until they have been fed a while on chopped 
liver. 

Maggots are produced and used in considerable numbers, sometimes 
as many as a bushel in a day. The fish eat them eagerly, and appear 
to thrive on them better than on dead meat. Having great tenacity of 
life, if not snapped up immediately by the fish they remain alive for a 
day or two, and, as they wriggle about on the bottom, are almost cer- 
tain to be finally eaten, which is a great gain in cleanliness and economy, 
as the particles of dead flesh falling to the bottom are largely neglected 
by the fish and begin to putrefy in a few hours and foul the troughs. 
As the growth of maggots can be controlled by regulation of the tem- 
perature, they may be kept all winter in a pit or cellar and used as food 
for fish confined in deep tanks not easily cleaned. 

In the rearing of maggots the offensive odors of decaying flesh may 
be partly overcome by putting it away in boxes, after the visits of the 
flies, and covering it with pulverized earth. Only flesh-eating maggots 
have yet been tried, and the trouble may possibly be rectified by culti- 
vating the larvae of other species, such as the house-fly, the stable fly, 
etc., or a little white maggot known to grow in heaps of seaweed, if 
their rate of growth is found to be satisfactory. 

Occasional use has been made of fresh fish for direct feeding, but when 
thrown into the water after chopping it breaks up into fibers to such 
an extent that it is not satisfactory, unless in a coarsely chopped form, 
for the food of large fish. A few barrels of salted alewives have been 
used, and, if well soaked out and chopped, they are readily eaten by the 
larger fish and can be fed to fry, but are less satisfactory with the latter, 
and, like fresh fish, break up to such an extent that they are only to be 
regarded as one of the last resorts. 

Fresh-water mussels, belonging almost wholly to a species of Unio, 
have been occasionally gathered with nets or dredges in the lake close 
to the station and opened with knives and chopped. The meat is 
readily eaten by all fishes and appears to form an excellent diet. It is 
more buoyant than any other article tried, sinks slower in the water, 
and gives the fish more time to seize it before it reaches the bottom; 
but the labor involved in dredging and shelling is a serious drawback. 

During the seasons of 1886 and 1888 some use was made of mosquito 
larvae, collected from pools of swamp water by means of a set of strain- 
ers specially devised for the purpose and from barrels filled with water 
disposed in convenient places near the rearing-troughs. The larvae (or 
pupae) were strained out and fed to the fish. No kind of food has been 



MANUAL OF FISH-CULTURE. 61 

more eagerly devoured, and apparently no other food has contributed 
more to the growth of the fish; but the time expended in collecting is 
out of all proportion to the quantity of food secured. Perhaps a series 
of breeding-tanks arranged in proximity to the fish-troughs, into which 
the water containing the larvae might be drawn when desirable by the 
simple opening of a faucet, would reduce the labor involved. 

Middlings and flour have been tried in combination with blood from 
the shambles, but did not appear to satisfy the fish so well as the vari- 
ous forms of meat, and their use has, therefore, not been continued. 
They were fed in the form of a pudding composed of two parts blood 
and one part flour or middlings, cooked carefully to avoid burning, 
and the mixture was then passed through a meat-chopper and ladled 
out with a spoon, like other chopped food. 

The growth of live food in the ponds themselves in which the fish are 
maintained has been the subject of study. Ponds several years old 
and well stocked with vegetation were at one time devoted to these 
experiments. They had been empty during the preceding winter, and 
in the spring were fertilized with various sorts of animal and vegetable 
refuse. They were stocked with different species of Crustacea native 
to the region, including shrimps (Gammarus) and entomostraca, of the 
genera DapJinia, Ceriodaphnia, Sida, Cyclops, Polyphemus, etc., which 
were systematically collected from open waters by nets and other appa- 
ratus and placed in the ponds. These forms all multiplied there, some 
of them enormously, but no means was found of inducing continuous 
or frequent reproduction of them, and the young fish soon exhausted 
the supply. 

In serving the food the attendant carries it with the left hand—in a 
2-quart dipper if chopped meat, in a larger vessel if maggots — and, 
dipping it out with a large spoon, strews it the whole length of the 
trough, being careful to put the greater portion at the head, where the 
fish nearly always congregate. Finely chopped food, for very young 
fish, is slightly thinned with water before feeding. 

It is usual to feed the meat raw except the lights, which chop better 
if boiled first; but occasional lots of meat, on the point of becoming 
tainted, are boiled to save them. All meats fed directly to the fish are 
first passed through a chopping-machine. To fish just beginning to 
eat, food is given four times a day, or in some cases even six times, but 
as the season progresses the number of rations is gradually reduced 
to two daily. In winter such fish as are carried through are fed but 
once a day. 

CLEANING THE TROUGHS. 

The troughs are all cleaned daily. When the hollow plug is drawn 
the water rushes out rapidly and carries most of the debris against the 
screen. The fishes are excited, and, scurrying about, loosen nearly all 
the dirt from the bottom ; what will not otherwise yield is started with 
a brush, but after the first few weeks the brush has rarely to be used 



62 EEPORT OF COMMISSIONER OF FISH AND FISHERIES. 

except to rub the debris through the outlet screen. Owing to the incli- 
nation of the trough, the water recedes from the upper end until the 
fishes lying there are almost wholly out of water, but, although they are 
left in that position sometimes for 10 or 15 minutes, no harm has ever 
been known to result. 

TRANSPORTATION AND LIBERATION OF YOUNO SALMON. 

The salmon produced at the station have, with few exceptions, been 
liberated in the Penobscot Eiver or its tributaries, and more than 90 
per cent of them in small tributaries within 10 miles of the station. 
They have been spread about in streams and lakes, at all accessible 
points. They are transferred in tin cans, holding about 8 gallons, with 
an extreme height, including neck, of 17 or 18 inches, and a body 15£ 
inches in diameter and 10 inches deep, making a very broad and low 
can, well adapted to the use to which it is put. Its great width favors 
aeration at the surface, and a good deal of dashing about of the water 
when on the road. The cans are filled to within about an inch from the 
shoulder, giving opportunity for the water to swash about and aerate 
itself. Into such a can are put from 200 to 400 Atlantic salmon seven 
months old, more or less, according to the size of the fish, the tempera- 
ture of the air, and the weather. The ordinary load is about 300 when 
the temperature of the water is 52° to 54° F., making 37 fish per gallon. 
Such loads are entirely safe for the conditions attending the work. 
The motion of the wagon in which they are carried keeps up the aera- 
tion of the water, so that the fish can not exhaust the air. Should the 
cans stand still a very long time aeration is effected by a force-pump 
which draws the water from the can and returns it through a tube so 
that it strikes upon a deflector by which it is broken and scattered in 
spray. The suction hose is covered with a roomy wire strainer, so that 
the fish are not drawn in. 

DISEASES. 

Salmon in all their stages of growth are subject to a variety of dis- 
eases. White spots sometimes occur on the eggs attached to the shell, 
but have no hold on the embryos, so that when the shell is torn off the 
white spot is seen as a cluster of globular white masses on its inner 
surface. These appear to be vegetable parasites, perhaps fungoid in 
their relations, and are never seriously abundant. Other white spots 
are connected with the yolk-sac itself. These are more serious, but 
while they result in the death of many embryos, they are by no means 
always fatal. In 1896 there were hatched at the station some rainbow 
trout that were badly spotted on the sac. A portion of the fry were 
divided into three lots for experiment: (a) Without spots; (&) moder- 
ately spotted; (c) badly spotted. They were kept separate through the 
season, and a fair percentage survived, as follows: Of lot a, 55 per 
cent ; of lot b, 59 per cent ; of lot c, 43 per cent. In the fall they were 



Report U. S. F. C. 1897, (To face page 63.) 



Plate 18. 




FUNGUS ON SALMON EGG 
(Enlarged 9 -times.) 



FUNGUS ON SALMON EGG, BEARING REPRODUCTIVE ORGANS. 
(Enlarged 9 times.) 




REPRODUCTIVE ORGANS OF EGG FUNGUS. 

(Enlarged 150 times.) 



MANUAL OF FISH-CULTURE. 63 

till weighed, and it was found that lot c had made a slightly better 
growth than lot a. 

One of the most uncontrollable diseases attacks salmon fry midway 
in the sac stage, and finishes its work before the complete absorption 
of the sac. The most evident symptom is the appearance of scattered 
white spots in the sac ; the fish cease to try to hide, but lie scattered 
about on the bottom of the trough ; the spots increase in size, coalesce, 
and finally occupy large areas, especially in the tip of the sac, which 
becomes quite white. Soon after this the fish dies. The attack on a 
lot makes rapid progress; for instance, a lot of 2,000 in which, up to 
April 22, the losses have been from 1 to 9 daily, will show 17 dead on 
the 23d, and five days later 360 die in a single day. In 1890 this epi- 
demic attacked especially the fry of Atlantic salmon, destroying about 
a third of them; it also destroyed many landlocked salmon, and some 
other species suffered heavily about the same time. In 1891 there was 
not a trace of it. In 1892 it returned again, and out of 305,353 fry of 
Atlantic salmon it left but 3,874, and these were by no means healthy ; 
but it attacked only Atlantic salmon. Salt and mud were tried as 
remedies, but though the progress of the disease appeared in some 
instances checked thereby, no permanent benefit resulted from their 
use. 

In 1890 this epidemic appeared to run in families. There was evi- 
dence tending to show that all the eggs coming from a particular mother 
would have a common degree of liability to the disease — some families 
being exterminated by it, some only decimated, and others able to resist 
it altogether. It did not appear to be infectious, as several lots of fry, 
separated by screens, would occupy a single trough, and in some cases 
those at the head of the trough would be totally destroyed, or nearly so, 
and those below them escape from attack. 

The only other diseases of Atlantic salmon that demand notice here 
are connected with the so-called fungus, belonging to the group of 
water molds called Saprolegnice, and probably to the genus Saprolegnia, 
one species of which, S.ferax, is noted as the cause of very destructive 
epidemics among the adult salmon of Scotch and English rivers. The 
species that attacks fish eggs is well known to every fish-culturist as 
a fine white growth of a cottony or woolly appearance that forms upon 
dead eggs, and when neglected spreads out so as to envelop in its 
threads a great many of the living eggs surrounding it. It is by no 
means certain that all such growths belong to one species or even to 
one genus, but they are much alike in structure and growth and live 
upon animal and vegetable matter, either as parasites attacking living 
matter or as saprophytes attacking only dead and decaying matter. 
There has never been serious trouble with this fungus at Craig Brook 
station, and great loss from it can only occur in consequence of neglect 
of the duty of picking out the dead eggs. An instance of its attacking 
a living egg except by reaching out from a dead one is unknown. Fish 



64 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 

several mouths old are sometimes afflicted with a similar growth, which 
may possibly be not the original cause of the disease, but ouly an 
attendant symptom. Such an attack was experienced at Craig Brook 
in July, 1888. The fry of Atlantic salmon were the sufferers and the 
mortality was considerable, but it yielded promptly to a salt bath. 

The occurrence of fungus on wounds, even on such as result from 
the abrasion of the skin or the loss of a scale, is very common, but such 
cases are rarely fatal, though no remedy be applied. The only serious 
attack of fungus on adult salmon occurred during the experimental 
work at Craig Brook in 1871. The first inclosure made to receive the 
breeding fish was a small and shallow one, made by damming the brook 
itself at a point Avhere its volume consisted of about 30 per cent of 
spring water. The fish had' suffered considerably from the handling- 
necessary in bringing them so far and from the rough character of the 
experimental cars in which they were transported. The first of them 
were placed in the inclosure June 8. On the 12th 2 of them died, on 
the 13th 2 more, and by the 17th 14 were dead out of 41 received; by 
the 20th the mortality had increased to such a point that it became 
evident that not a single salmon would survive unless some change was 
made in the mode of confining them, and they were all removed and 
placed in other quarters. Nine of them, already so badly diseased as 
to be considered hopeless cases, were turned loose in Craig Pond, and 
part of these recovered and spawned in the autumn following on a 
gravelly shore, where some of them were taken and found to bear the 
well-healed scars of their ugly sores. 

The symptoms noted were sluggishness and heedlessness; an inclina- 
tion to swim near the surface of the water; a white, filmy appearance 
of the eyes, which seemed to be accompanied or followed in many cases 
by blindness; a white fungoid growth on the abraded tips of the fins 
and wherever the scales had been rubbed off; white blotches breaking 
out on all parts of the body, even where there had been no mark of 
injury, particularly on the head, proving on examination to be patches 
of white fungus, which, on the parts of the body covered by scales, 
grew underneath the latter and pushed them from their places. 

Experiments in confining salmon in other waters the same season 
turned out successfully, and it seems that the most important condi- 
tions in the case were these: The area of the fatal inclosure was about 
a quarter of an acre; the water was partly from springs and was so 
exceedingly transparent that a pin dropped into it could be readily 
seen at a depth of 6 feet, so that there was practically no protection 
from the rays of the June sun ; the fish had been transported in a com- 
mon dory with holes bored in the bottom to admit water, a very inferior 
sort of car compared with those now in use; they had been transported 
a long distance and passed three separate locks and had finally been 
hauled in a tub on a cart over rough ground from Alamoosook Lake to 
the inclosure. 



MANUAL OF FISH-CULTURE. 65 

The conditions at Craig Pond, where some of the worst cases recov- 
ered, were these: An area of 231 acres ; a maximum depth of 69 feet; 
exceedingly pure and transparent water, like that of the inclosure. 

At two of the other inclosures tried that summer, where there was 
no attack of fungus, the water was brown and dark, like that of ordi- 
nary brooks and ponds, and in the remaining one it was intermediate 
in character. 

These facts point strongly to the character of the water as the cause 
of the fatality of the disease, and especially to its pellucid character, 
which exposed the salmon to an extraordinary glare of light, whereby 
the growth of the pest was greatly encouraged. The recovery in the 
transparent water of Craig Pond was rendered possible by the great 
depth of the water, through which but a small fraction of the light of 
day could penetrate. No doubt the salmon liberated there at once took 
refuge in the deeper parts. The suggestion naturally arises that arti- 
ficial shade might be useful in the treatment of such diseases, whether 
the attacking fungus be identical with that observed in the above in- 
stances or a related one. 

It is certain, from the promptness with which dead animal matter 
becomes the prey of saprophytic growths, that the spores of these 
water-molds are well disseminated throughout fresh waters, everywhere 
ready to seize upon an opportunity for germination and growth, and 
that as a general rule these spores are quite unable to seize upon any 
animal substance which is not already dead or in a diseased condition. 

A growth of Saprolegnia ferax once established on the body of a 
salmon is able to extend itself upon and into the living tissues around 
it, which it seizes upon and destroys. Growing upon a dead egg, it not 
only ensnares the neighboring living eggs, but sometimes pierces their 
shells and establishes itself on the internal parts. In one instance the 
fungus had gone so far as to attach itself to a living embryo, which, on 
removal from the shell, was found to support on the sac quite a tuft of 
growing fungus, though neither on the sac nor any other part of the 
fish was a trace of dead substance discernible. 

It has been ascertained that the Saprolegnia which attacked the 
living salmon can be communicated by contact to dead flies, and that 
Saprolegnia found growing in the ordinary way on dead flies in water 
can be communicated iu its turn to living and healthy dace and may 
so flourish on them as to cause their death. 

The impression has prevailed that the Saprolegnia which infests the 
eggs in hatching-troughs originates in or is encouraged by bare wood 
exposed to water, and that special effort is necessary to prevent its 
forming; but experience at this station does not show that attacks of 
fungus on either eggs or fish could be traced to bare wood, and, on the 
other hand, eggs and fish in troughs carefully varnished with asphaltum 
are no freer from fungoid or other disease than those in neighboring 
troughsfrom which long use had worn almost the last vestige of varnish. 

F. C. K. 1897 5 



66 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 

The best precaution against this growth is the careful picking out of 
dead eggs before there is time for the fungus to grow on them, and in 
case of a serious attack on fry or older fish to treat them with an exterior 
application of salt, which, while not a cure-all, is very efficacious in 
cases of fungous diseases, and, if prudently used, a safe remedy for fish 
that have reached the feeding stage. 

To apply this remedy to fry in the troughs a saturated solution of 
salt in water is made — that is, the strongest brine that can be made with- 
out heating the water. The flow of water in the trough to be treated 
is then stopped, which leaves it from 3 to 4 inches deep, when enough 
brine is poured in to make the water in the trough about as salt as com- 
mon sea-water, about 1.028 specific gravity. The fish are left in this 20 
or 30 minutes, unless they exhibit uneasiness, and then fresh water is 
turned on. Precaution is taken to dilute the brine with an equal quan- 
tity of water, to distribute it the whole length of the trough, actively 
stirring the water to secure an even mixture; and before turning on the 
usual water supply, a large quantity of fresh water is likewise poured 
in, distributing it the whole length of the trough and stirring as before, 
to guard against a too sudden change. 

Such precautions are especially necessary in the application of salt 
to very young fish. A large number of salmon in the sac stage was 
once destroyed by pouring in a little brine without stirring it; it ap- 
peared to sink to the bottom and spread out in a layer by itself among 
the fry, and all exposed to it died. 

ENEMIES OP YOUNG SALMON. 

The young salmon are subject to the attacks of many animals and 
birds, such as the mink, mole, star- nosed mole, common rat, muskrat, 
kingfisher, great horned owl, great blue heron, sandpiper, and fish- 
hawk, besides frogs and all large fishes. 

At Craig Brook the mink has caused serious loss in the ponds. As 
a protection some of the ponds are covered with galvanized poultry 
netting, and traps are kept constantly set in the avenues by which it 
is apt to approach. The mole burrows through embankments and thus 
sometimes causes trouble. The star-nosed mole is known to steal dead 
eggs, and is suspected of taking live ones. The rat sometimes takes 
young fish from the troughs. The muskrat burrows in embankments 
and sometimes eats fish. 

The different fish-eating birds occasionally steal fish from the ponds 
or troughs, but if a careful watch is kept the danger is not great. 
Frogs may be exceedingly destructive to young salmon, and must be 
caught out of the fish-ponds. 

To avoid loss from cannibalism among the fishes it is necessary to 
feed them well and to take great care that no large fish get in among 
the small ones. 



Report U. S. F. C. 1897. (To face page 67.) 



Plate 19. 




TAKING SPAWN OF LANDLOCKED SALMON AT GRAND LAKE STREAM, MAINE. 



THE LANDLOCKED SALMON. 



The landlocked salmon was formerly regarded as specifically distinct 
from the seagoing form, but it is now generally considered only a vari- 
ety. The fish found in Sebago Lake and other localities in the United 
States is known as Salmo salar sebago, and the Canadian form as Salmo 
solar ouananiche. From the fish-culturist's point of view, however, the 
marked difference between the landlocked and the seagoing salmon in 
habits and growth must separate them as widely as any two species of 
the same family. 

Landlocked salmon are known to exist only in some of the lakes in 
Sweden, besides the lakes of eastern North America. They are native 
to most of the lakes of eastern Labrador, including the waters tribu- 
tary to Ungava Bay, and find their western limit in Lake St. John and 
vicinity, on the Saguenay Eiver. Those of the latter district have been 
much written about under the name of "ouananiche." 

Doubtless the absence of the migratory instinct is at the bottom of 
most of the variations from the normal type of Salmo salar which the 
landlocked salmon exhibits. The lakes afford a far poorer feeding- 
ground than the sea; hence, j>erhaps, the diminutive size and leaner 
flesh of the landlocked salmon. Its lower tone of color, less permanent 
sexual marks, and greater liability to ovarian disease, as well as differ- 
ent habits of feeding, may perhaps be referable to the same general 
cause. There are some other peculiarities, however, which are not so 
easily explained. For instance, the eggs of the landlocked salmon are 
considerably larger than those of the sea salmon, and the very young 
fry are correspondingly larger. 

The growth of the young of the Sebago landlocked salmon seems to 
be more rapid than that of the anadromous salmon, for some specimens 
more than a foot long still bear on their sides dark, transverse bands, 
characteristic of young salmon; but it may be that the landlocked fish 
simply retain the marks of the immature stages to a later period of life. 
This view is supported by the fact that the dark bands are never com- 
pletely obliterated from the sides of the landlocked salmon, being always 
very distinct, even in adult specimens, on the under side of the skin, a 
character absent among migratory salmon. 

The landlocked salmon is smaller and more slender than the anadro- 
mous salmon, but its flesh is fat and rich and of a very delicate flavor. 
In game qualities it is, for its size, quite the peer of the larger salmon, and 
affords keen sport to the fly fisherman. It is, therefore, much sought 
after, and ranks in public favor among the foremost fresh- water species. 

67 



68 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 

The natural range of the landlocked salmon in the United States is 
much restricted. Leaving out of the question the salmon formerly 
frequenting the rivers tributary to Lakes Ontario and Champlain, the 
extent of whose migration is a matter of doubt, we find them only in 
four limited districts, all in the State of Maine, namely, the Presumpscot 
River (including Sebago Lake) in Cumberland and Oxford counties, the 
Sebec Eiver (a tributary of the Penobscot) in Piscataquis County, the 
Union River in Hancock County, and the St. Croix River in Washing- 
ton County. There are some minor differences between the fish of these 
several districts, of which, perhaps, that of size is most notable. The 
Sebago and Union River fish are much larger on the average than those 
of the Sebec and St. Croix. The Sebago salmon average at the spawn- 
ing season 4 or 5 pounds weight for the males and a pound less for the 
females, while specimens of 12 and 14 pounds weight are not rare, and 
there is a record of one of 17£ pounds. The Union River fish are 
about the same size. 'The St. Croix fish vary in the matter of weight in 
different parts of their range, but the average weight of either sex at 
Grand Lake Stream is a little less than 3 pounds; specimens of over 6 
pounds are rare, and none is on record of over 10 pounds. 

After attempts to collect eggs of landlocked salmon in each of the 
four regions mentioned, it was found that Grand Lake Stream in 
the St. Croix district afforded excellent facilities for this work. The 
hatching station at that place was operated continuously from 1875 
to 1892. Since 1892 the station has been closed and the propagation 
of landlocked salmon by the United States Fish Commission has been 
conducted at Green Lake station. 

The following notes on fish-cultural methods have special application 
to Grand Lake Stream : 

The landlocked salmon of the St. Croix, though originally well dis- 
tributed through the lakes tributary to that river and still inhabiting 
a great many of them, finds in some a much more congenial home 
than m others, its favorite abode being Grand Lake on the Schoodic 
River. This body of water is of irregular shape, about 12 miles in 
length and 4 in extreme breadth, fed almost wholly by short streams 
that form the outlets of other lakes, and from this cause, as well as 
from the fact that it drains a gravelly country and is girt with clean, 
rocky shores, it is one of the purest of the Maine lakes. Its greatest 
depth is believed to be a little more than 100 feet. Its outlet is Grand 
Lake Stream, a shallow, rapid, gravelly stream, about 3 miles long, to 
which the salmon go in October and November to deposit their eggs. 
Comparatively few of the salmon of this lake resort to the streams 
tributary to it. 

The operations with landlocked salmon necessarily differ from those 
with migratory salmon. Being at home in fresh water and having there 
their feeding-grounds, they continue to feed until the close approach 
of the spawning time, and hence they could not be penned up in the 
summer without some provision for an artificial supply of food, which 
would probably involve a great deal of expense and trouble. More- 



MANUAL OF FISH-CULTURE. 69 

over, the necessity of collecting- breeding fish early in the summer does 
not exist, because they are at no time more congregated and easy to 
catch than at the spawning season. 

Their capture is easily effected by stretching a net across the outlet 
of the lake and leading them through a tunnel-formed passage into an 
inclosure of netting. There happens to be at this point a wide surface 
of smooth bottom, with water from 1 to 3 feet in depth, affording an 
excellent site for spacious inclosures, not only for entrapping but for 
assorting and storing salmon during the spawning season. Nets are 
generally stretched across the stream (to keep the fish back in the 
lake) immediately after the beginning of the close season, September 15. 
The earliest of them begin to spawn before the end of October, but the 
actual inclosing of the breeding stock is deferred until the early days 
of November. The taking of spawn generally begins about November 
6 and continues two or three weeks. Commonly by November 20 or 22 
this work is completed, and the breeders are carried a mile or two up 
the lake and liberated. 

The method of manipulation is the same as at the Craig Brook station, 
and does not differ materially from that adopted by all the American 
breeders of JSalmonidce. The results in the impregnation of the spawn 
are not so uniformly satisfactory as with sea salmon. There appears 
to be a greater prevalence of ovarian disease than among the migratory 
salmon. The occurrence of white eggs among the normally colored 
and healthy ones as they are yielded by the fish is very common, and 
occasionally the entire litter is defective. It is not improbable that 
some eggs are incapable of impregnation, though exhibiting no visible 
signs of disease. However, the general result is satisfactory, the ratio 
of impregnated eggs being from 93 to 95 per cent. 

The facilities for developing and hatching the eggs at Grand Lake 
Stream are rather poor. No good site could be found by the side of 
the stream, no suitable brook could be found near enough to the fishing- 
grounds, and the neighboring springs lacked either volume or facilities 
for utilization. Of three hatcheries, two use spring water exclusively, 
and one of them lake or stream water exclusively. The lake water is 
preferred, but unfortunately it can only be used for the slow develop- 
ment of part of the eggs, circumstances connected with the floating of 
timber down the stream compelling the evacuation of that hatchery in 
March. The main hatchery is well located except that the water is from 
springs, and this unfavorable circumstance is well counterbalanced by 
the facilities for aeration, which are very good and very fully employed. 
The eggs are placed upon wire-cloth trays in stacks or tiers, ten deep, 
and arranged for a free horizontal movement in the water. 

The egg shipments are made in January, February, March, and some- 
times in April. The eggs hatched are selected from those that have 
been retarded in development; the fry reach the age for liberation in 
June, when their natural food is believed to be abundant. 



70 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 

Experience at Green Lake lias supplied some interesting data. Here 
we find the breeding- grounds of the salmon both in the affluents and in 
the effluent of the lake, but, unlike Grand Lake, mainly in the affluents. 
Great Brook, the largest tributary, is most resorted to, and on this 
stream is located the station of the United States Fish Commission. 
The most of the breeders are taken in a trap in the brook, which 
they readily enter when seeking to ascend to their natural breeding- 
grounds just above. The trap is constructed of wood and close to it, 
also in the bed of the brook, are numerous pens of the same material 
in which the fish are assorted and held during the spawning season. 
On the bank, snug by the pens, is the spawn-house, and a few rods 
away is the hatchery. The hatchery is supplied with water from Eocky 
Pond, the source of Great Brook, by a wooden flume 7,050 feet long, 
supported by wooden trestles, at some points elevated many feet above 
the ground. In cold weather the water cools off 1J degrees in passing 
down this flume; in warm weather it warms up 1£ degrees. Though 
the summer temperature during the early years of the station was 
sometimes over 80° F. and some other species succumbed to the heat, 
the landlocked salmon endured it safely, and the only notable effect on 
them was that at 75° and upward the adults reared in the station ponds 
refused to eat. 

As at the Schoodic station, among the adult wild salmon caught 
for breeding each year are many more females than males. In 1889 
the proportion was 3 females to 2 males ; in 1893 it was 9 to 4. The 
size of the Green Lake salmon is remarkable; the mean of 69 full-roed 
females in 1889 was 7.8 pounds in weight and 25.5 inches in length; the 
males the same year averaged 5 pounds in weight and 22.3 inches 
in length; one female weighed 11 pounds 9 ounces, and measured 30 
inches; another, 11 pounds 6 ounces in weight, was 30£ inches in 
length; one male, 31 inches long, weighed 13 pounds 8 ounces. The 
number of eggs yielded by the females is about 4,000 each. 



Report U. S. F. C. 1897. (To face page 71.) 



Plate 20. 



'■■■e(r. m0mww00 f V ,, 

V*\\/ ' ' ' ' %J//i9 




THE RAINBOW TROUT. 



DESCRIPTION OF THE FISH. 

The body of the rainbow trout (Salmo irideus) is comparatively short 
and deep, and is more elongate in males than in females. The average 
depth is contained about three and four- fifths times in the body length. 
The short head, which is obtusely ridged above, is about one-fourth the 
total length. The mouth is smaller than in other species of Salmo, the 
maxillary reaching scarcely beyond the eye, which is rather large, and 
is contained five times in the side of the head. The caudal fin is dis 
tinctly but not strongly forked. On the vomer are two irregular series 
of teeth. The dorsal rays number 11 and the anal 10. In the typical 
species there are about 135 scales in the lateral series, with 20 rows 
above and 20 below the lateral line; in the several subspecies the 
number of rows of scales along the side is from 120 to 180. The color is 
variable, depending on sex, age, and character of water. Typical adult 
fish are bluish above, silvery on the sides, profusely and irregularly 
dark-spotted on the back and sides, the spots extending to the vertical 
fins, with a red lateral band and blotches and a nearly plain belly. The 
sea-run fish are nearly plain silvery. The chief distinguishing color 
characteristics of the varieties are in the number and position of the 
spots. 

RANGE AND VARIATION. 

The rainbow trout is not indigenous to eastern waters, its original 
habitat being the Pacific coast of the United States. It is especially 
abundant in the mountain streams of California. A few specimens, 
however, have been taken in saltwater, and it is not unlikely that some 
find their way through the rivers into the sea. 

The species is subject to considerable variation in form and color in 
different parts of its range, and the following varieties have received 
recognition by ichthyologists: The brook trout of western Oregon and 
Washington (Salmo irideus masoni), which rarely weighs as much as a 
pound and is locally abundant in the streams of the Coast Eange from 
Puget Sound to southern Oregon; the McCloud Eiver trout (Salmo 
irideus shasta), which attains a large size, is abundant in the streams of 
the Sierra Nevada Mountains from Mount Shasta southward, and is the 
rainbow trout which has received most attention from fish-culturists; 
the Kern River trout (Salmo irideus gilberti), which attains a weight of 
8 pounds, and is found only in Kern River, California; the noshee or 
nissuee trout (Salmo irideus stonei), which inhabits the Sacramento 
basin, and reaches a weight of 12 pounds; the golden trout of Mount 
Whitney (Salmo irideus aqua-bonita), which inhabits streams on both 

sides of Mount Whitney, California. 

71 



72 EEPORT OF COMMISSIONER OF FISH AND FISHERIES. 

In the extensive section of the West in which the fish abounds its 
name varies in different localities ; "red sides," "mountain trout," 
"brook trout," and "golden trout," besides "rainbow trout," are some 
of the popular appellations, while in the States east of the Mississippi 
River it is generally called " rainbow trout" or "California trout." 

TRANSPLANTING. 

The rainbow trout has been successfully transplanted in many of the 
mountain streams in different parts of the United States, where it 
grows and multiplies rapidly, as is shown by the many favorable 
reports. The best results, however, seem to have been obtained from 
plants made in streams of Michigan, Missouri, Arkansas, throughout 
the Alleghany Mountain ranges, and in Colorado, Nevada, and other 
Western States. It was introduced into eastern waters by the United 
States Fish Commission in 1880, but it is possible that specimens of it, 
or its spawn, had been brought east prior to that time by some of the 
State commissions or by private enterprise. 

It is believed that this species will serve for stocking streams for- 
merly inhabited by the brook trout (Salvelinus fontinalis), in which the 
latter no longer thrives, owing to the clearing of the lands at the 
sources of the streams, which has produced changed conditions in and 
along the waters not agreeable to the brook trout's wild nature. The 
rainbow is adapted to warmer and deeper waters, and is therefore 
suited to many of the now depleted streams which flow from the moun- 
tains through the cultivated lands of the valleys. 

Eainbow trout differ widely from brook trout and other pugnacious 
fishes, in that they feed principally upon worms, larvse, Crustacea, and 
the like, and do not take readily to minnows as food. They should be 
planted in spring or early summer, when their natural food is abun- 
dant, as they will then grow more rapidly and become accustomed to 
life in the stream; and when worms, larvae, etc., are no longer to be 
found, their experience and size will enable them to take a minnow or 
anything that may present itself in the shape of food. 

In the Eastern States fry should not be planted in open waters until 
they are several months old, and then not until the temperature of the 
streams begins to rise; but fish hatched in December and January can 
safely be planted in April and May. On the Pacific slope the fry may 
be successfully liberated at any time after the umbilical sac is absorbed. 

SIZE AND GROWTH. 

The size of the rainbow trout depends upon its surroundings, the 
volume and temperature of the water, and the amount of food it con- 
tains. The average weight of those caught from streams in the East is 
probably less than a pound, but some weighing 6§ pounds have been 
taken. In the Ozark region of Missouri they are caught weighing 5 to 
10 pounds. In some of the cold mountain streams of Colorado their 
average weight is not more than 6 or 8 ounces, but in lakes in the 



Report U. S. F. C. 1897. (To face page 73.) 



Plate 21. 




MANUAL OF FISH-CULTURE. 73 

same State, where the water becomes moderately warm in summer 
and food is plentiful, they reach 12 or 13 pounds, fish of this size being 
from 25 to 28 inches long. In the Au Sable Eiver, in Michigan, they 
attain a weight of 5 to 7 pounds. In their native streams of California 
they are often caught ranging from 3 to 10 pounds, but average from 
1 to 2 pounds. The largest specimen ever produced in the ponds at 
Wytheville, and fed artificially, weighed 6£ pounds, but many others in 
the same ponds weigh from 1 to 3 pounds. 

The average growth of the rainbow trout under favorable artificial 
circumstances is as follows: One year old, from f to 1 ounce; 2 years 
old, from 8 to 10 ounces; 3 years old, from 1 to 2 pounds; 4 years old, 
from 2 to 3 pounds. They grow until they are 8 or 10 years old, the 
rate diminishing with age. Some grow much faster than others under 
the same circumstances, but the rate of growth is largely a question of 
food, temperature of water, and extent of the range. In water at 60°, 
with plenty of food, fish 1 or 2 years old will double their size several 
times in a single season; while in water at 40°, with limited food, the 
growth is scarcely perceptible. 

The rainbow, like the brook trout, will live in water with a compara- 
tively high temperature if it is plentiful and running with a strong 
current, but sluggish and shallow water, even with a temperature of 
70° F., is dangerous for brook trout. Rainbow trout will live in warmer 
water than brook trout, and are found in swift, rapid streams at 85° F., 
especially where there is some shade, but in ponds tha.t temperature is 
dangerous even with shade and a good current. In its natural condi- 
tion this trout is usually found in water varying from 38° F. in winter 
to 70° F. in summer, and in selecting a site for a trout hatchery spring 
water with a temperature of 42° to 58° is required. 

The rainbow trout is a superior game fish, a vigorous biter, and fights 
bravely for liberty, though in the East it is somewhat inferior to the 
brook trout in these respects. 

SPAWNING-PONDS. 

In constructing ponds, one of the first considerations is to place the 
fish absolutely under the control of the fish-culturist, that he may be 
able to handle them without delay or inconvenience. At Wytheville 
they are constructed entirely of wood, about 15 by 50 feet and 3 to 3£ 
feet deep, and shaped as shown in plate 22, and have been found very 
satisfactory. Excellent water circulation is obtained in all parts, and 
there are no corners for refuse to lodge in. The bottom of the pond is 
built with a gradual elevation, in the direction of the upper end, of 2 
inches in the entire length of the pond. This makes it practically self- 
cleaning; nearly all of the foul matter will pass off and any remainder 
can be disposed of by drawing the water down low for a short period 
and then flushing the pond with fresh water. This method obviates the 
necessity of handling the fish, which is very important, especially when 
near the spawning time. 



74 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 

A guard-rack made of thin, narrow slats is arranged on an incline of 
about 45°, as shown at C. If the water is to be used again in ponds 
below, a receiver is built underneath the bottom of the pond at the 
lower end, between the foot of the guard-rack and the dam-boards, 
and the floor of the pond immediately over the receiver is cut away and 
fitted with a grating. This allows matter to fall through the receiver 
and from there it is washed through the sluiceway, which taps the 
receiver by drawing the gate shown at D. The sluiceway, E, is 
covered and leads off to a general waste-ditch. 

The pond is provided with a spawning-race about a foot deep, 4 feet 
wide, and 25 feet long, placed at the upper end of the pond, as shown 
at H. Three division boards (shown at F), about 12 feet long and of 
suitable width to come within 1 or 2 inches of the surface of the water 
when the pond is filled, are firmly fixed at the bottom. The object of 
these boards is to form four avenues leading to the raceway, so that 
one or two pugnacious fish can not command the approach and keep 
back spawning fish inclined to enter. There is a dam across the race- 
way about 4 inches high (shown at G) for the purpose of bringing the 
water to that depth in the lower end, so that when the trout enter they 
will find sufficient water in which to swim freely, and not be inclined 
through fear to return to the pond. 

The water in the pond is of sufficient depth to bring its surface 
within 6 inches of the top of the dam in the raceway, which will give 
the fish, in entering the raceway, a jump of 7 inches, allowing 1 inch 
for the depth of water on the dam in the raceway. This distance has 
been found more satisfactory than any other, and spawning fish alone 
will go up. If a jump of less than 7 inches is given, other fish can 
enter the raceway without much exertion, and will ascend and disturb 
the breeding fish, which, when spawning, should be kept strictly by 
themselves. 

There is no rule regarding the supply of water that applies to a 
spawning-pond at all times and in all places. It is necessarily gov- 
erned by the temperature of the water, size and shape of the pond, 
size of the fish to be supported, the amount of shade, etc. For a 
pond such as has been described, where water is plentiful, at least 200 
gallons per minute should be provided, with not less than 75 gallons 
per minute as a minimum, even where the temperature is from 50 to 
55 degrees and all other conditions are favorable. While the former 
amount is not absolutely necessary for the support of the fish, it 
insures the pond being kept clean and the fish are more inclined to 
enter the raceway at spawning time. In order to maintain an even 
temperature in the pond the earth is banked against the sides and 
ends, covering the framework shown on plate 25, and the embankments 
are made broad enough on top to admit of a good footway around the 
ponds. 

Such a pond as this can accommodate from 1,000 to 1,500 breeding 
fish. Fish must not be overcrowded, and in estimating the capacity of 



Report U. S. F. C. 1897. (To face page 74.) 



Plate 22. 




MANUAL OF FISH-CULTURE. 75 

a poiid several modifying conditions must be considered, such, as the 
size of the fish, water supply, temperature, and shade. In stocking the 
spawning-pond a good proportion is two females to one male. The 
breeding stock is selected carefully every year ; only sound and perfect 
fish are retained for the next season, and the blind and emaciated 
fish of both sexes are destroyed. 

TAKING THE SPAWN. 

The spawning season varies with the locality and the temperature of 
the water. It is usually two to four weeks later in the streams than 
where the fish are kept confined in spring water. In the ponds at 
Wytheville the spawning fish may be found any time after the 1st of 
November ; the season is well started by November 15, and generally 
closes about the 1st of March. December and January are the best 
months. In California the season extends from the 1st of February to 
May, and in Colorado begins early in May and continues until July. 

The natural nests of these fish are made on gravelly bottoms, and 
are round or elongated depressions about the size of a dinner plate. 
After the eggs have been deposited and fertilized they drop between 
the pebbles of the nest, where they lie protected until hatched. 

Where spawning-ponds are provided with suitable raceways the fish 
will ascend from the ponds into them, seeking a place to make their 
nests, and may then be taken out and stripped of their spawn. To take 
the fish from the raceway, a square net (I, plate 22) is dropped in on 
the cleats nailed against the side walls in the approach, shown at J, the 
dam in the mouth of the raceway is raised, and the fish driven back 
into the net. The net is then lifted out of the water, and if it contains 
too many fish to handle conveniently a landing-net is used to take out 
part of them before the square net is moved. The ripe fish are then 
placed in tubs or other vessels provided for the purpose. If too many 
fish are put in the tub at one time they become restless and sick before 
they can be stripped of their spawn. 

There are two methods of taking and impregnating the spawn of 
fishes, the "wet" and the "dry" methods. By the "wet" method the 
eggs are taken in a pan containing sufficient water to cover them and 
allow them to mix freely with the milt, which is immediately added. 
After the contents of the pan have been stirred for a few seconds with 
a feather, the eggs are set aside and left undisturbed during fertiliza- 
tion. The "dry" or " Russian" method is nowin general use; the eggs 
and milt are taken in a moist pan and it makes little difference which 
is taken first, but one should immediately follow the other, and the 
contents of the pan be thoroughly mixed. 

After the eggs and milt have had time for contact, and before the 
eggs begin to adhere to the bottom of the pan, water is added to 
the depth of about an inch, the eggs being kept in gentle motion, by 
turning the pan, to prevent adhesion. After 2 or 3 minutes the milt 



76 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 

is poured off and clear water is put in the pan, in which the eggs are 
allowed to remain until they separate, which will be in from 15 to 45 
minutes, depending on the temperature of the water. It is preferable 
to take the eggs to the hatchery before the milt and water are poured 
off, and there rinse them off and place them directly on the hatching- 
trays (previously arranged in the troughs) and then allow them to 
separate. In freezing weather it is advisable to strip the eggs in water 
or to use two pans, one set in the other, with water in the bottom pan 
to prevent the eggs from being chilled. 

In taking spawn the manipulation of the fish without injury is a very 
delicate and exacting task, full knowledge of which can only be 
acquired by experience, as it is difficult to squeeze the spawn from the 
fish without injuring or even killing it. In taking hold of the fish in 
the spawning-tub the operator catches it by the head with the right 
hand, the back of the hand being up, and at the same time slips the 
left hand under the fish and grasps it near the tail, between the anal 
and caudal fins. A fish caught in this way can be easily turned over 
as it is brought out of the water, so that its abdomen is up and in the 
proper position for spawning by the time the spawning-pan is reached. 
If the fish struggles it must be held firmly, but gently, until it becomes 
quiet, and when held in the right position it will struggle only for a 
moment. A large fish may be held with its head under the right arm. 

When the struggle is over the right hand is passed down the abdo- 
men of the fish until a point midway between the pectoral and ventral 
fins is reached, then with the thumb and index finger the abdomen is 
pressed gently, and at the same time the hand is slipped toward the 
vent. If the eggs are ready to be taken they will come freely and 
easily, and if they do not, the fish is put back in the pond until ready to 
spawn. If the eggs come freely from the first pressure the operation 
is repeated, beginning at or near the ventral fin. 

After the first pressure has been given, by holding the head of the 
fish higher than the tail, all of the eggs that have fallen from the 
ovaries and are ready to be expressed will fall into the abdomen, near 
the vent, so that it will not be necessary to press the fish again over 
its vital parts, the eggs having left that portion of the body. All of 
the eggs that have fallen into the abd« imen below the ventral fin can 
be easily ejected without danger of injury to the fish, caused by unnec- 
essary pressure over its important organs after the eggs have left that 
part of the body. If these directions are judiciously and carefully fol- 
lowed but little, if any, damage will result; and, as an illustration, it 
may be mentioned that fish have been kept for 14 years and their full 
quota of eggs extracted each season during the egg-producing term, 
which is normally from 10 to 12 years. The male fish is to be treated 
very much in the same manner as the female, except the milt must not 
be forced out, only that which comes freely being taken. 

After stripping, the fish are not returned to the spawning-pond, but 
spent females are placed in one pond and the males in another. The 



Report U. S. F. C. 1897. (To face page 77.) 



Plate 23. 




MANUAL OF FISH-CULTURE. 77 

males are very pugnacious at this season, and sometimes fight for an 
hour or more at a time, until they are entirely exhausted; they run at 
each other with open mouths, lock their jaws together, and in that 
position sink to the bottom of the pond, where they lie for a short time, 
each holding the other in his grasp until rested, when they rise and 
resume the combat. As their teeth are abnormally long, they scar 
each other and even bite pieces of skin and flesh from the sides of their 
antagonists. 

The males are good breeders at 2 years old, but very few females 
produce eggs until the third season, when they are from 30 to 36 months 
old. At Wytheville hatchery about 1 per cent of the females spawn at 
2 years of age; about 50 per cent at 3 years, and about 85 per cent 
each season after that. About 15 per cent of the fully matured females 
are barren each season. It was at one time thought that the same 
individuals were barren each year, but experience has shown that 
such is not the case, as fish which were barren one season have been 
held over, in a separate pond, until the following year, when a large 
portion, if not all, produced eggs. This sterility may be the result of 
injuries received during the previous season, during the progress of 
spawning. 

EGGS. 

The number of eggs produced in a single season depends upon the 
size and age of the fish. The maximum from one 3 years old, weighing 
£ to 1£ pounds, is from 500 to 800; from one 6 years old, weighing 2 to 4 
pounds, it is 2,500 to 3,000. The eggs vary in size from 4£ to 5 eggs to 
the linear inch, and are of a rich cream color when first taken, changing 
to a pink or flesh-color before hatching. 

THE HATCHING-TROUGHS AND TRAYS. 

The eggs of rainbow trout are usually incubated on trays, placed in 
the water in troughs of various sizes and shapes. At Wytheville the 
troughs are set in pairs, as shown on page 78, are made of the best 
pine lumber, dressed to 1£ inches thick, and are 15 feet long, 14 inches 
wide, and 8 inches deep; 14 inches from the lower end inside is a 
guard-screen of x>erforated tin or wire mesh, fastened on a frame exactly 
fitted across the trough. Tin with perforations of -^ inch for very 
young fry, and larger ones as the fish grow, is preferable to wire. The 
screen is arranged to slide vertically between beveled cleats, that it 
may be kept clean easier. A plain board 3^ inches wide is placed 4 or 
5 inches from the lower end of the trough to serve as a dam. 

In the upper end of the trough horizontal screens (B, page 78), made 
of perforated tin, are used. These are so constructed that they can be 
slipped forward or raised up (as shown in the illustration) in feeding the 
fry or cleaning the troughs, and the water falling on a small wooden 
block in the center of the screen is thoroughly aerated before entering 
the trough. This arrangement possesses many advantages over the old 
method, where the screens were vertical, or nearly so, as it permits the 



78 



REPOET OF COMMISSIONER OF FISH AND FISHERIES. 



fish to ascend to the head of the trough and receive the water as it falls 
from the screen, which is very beneficial. Its use not only keeps the fry 
clean even in muddy water, but also reduces the loss of fry from suffo- 
cation in the early stages, caused by their banking around the vertical 
screens, and obviates the necessity for trough covers to prevent jumping, 
as trout rarely jump where the horizontal screen has been adopted. 




LONGITUDINAL SECTION OF HATCHING TROUGH.SHOWNG POSITION OF HATCHING TRAYS, DAM, ETC. 



Hatching-troughs, Guard-screen, etc. 
Hatching-trays (0), made about twice as long as wide, i. e., 28 by 
13^, are convenient to handle and adjust in the troughs. The sides 
of the frame are made of good pine lumber, dressed, 1 inch square; 
the ends are dressed \ by 1 inch, and are cut into the sides to form a 
smooth surface on the bottom for the wire filling. The wire used on 
the trays is woven with 8 threads to the inch, with a mesh § inch long, 
and should be. well galvanized after it is woven, in order to prevent 
rusting at the laps. 



Report U. S. F. C. 1 897. (To face page 79.) 



Plate 24. 




MANUAL OF FISH-CULTURE. 79 

Four hatching-trays are placed in each trough and are secured by 
keys or wedges:, and should be from 1 to 2 inches lower at the end next 
to the head of the trough, as shown at D, D, D, D, page 78. If placed 
in this way, e^ch tray will hold from 12,000 to 15,000 eggs with safety. 
Muddy water during the hatching season necessitates the use of a tin 
tray with a perforated bottom (shown at E, page 78), which is 13§ inches 
wide and 32 inches long. This sets inside of the hatching-trough on 
feet raising it an inch above the bottom of the trough. The hatching- 
tray containing the eggs is placed inside and rests on the brackets 
shown at G. The fish, as they hatch out, fall from the hatching-tray 
upon the perforated bottom of the tin tray, and by their movements 
work the sediment through, leaving them on a clean bottom and in no 
danger of being smothered. The tin trays are also useful in counting 
fish, or in holding small lots of fish of different species in the same 
trough. Where supplementary trays are not used, the fry fall directly 
into the troughs. 

Troughs 15 feet long will admit of four hatching-trays in a single 
row, each of which will safely carry 12,500 eggs, making 50,000 to a 
trough; this is enough to work easily, but if it is necessary to make 
more room a double row of trays may be put in, one tray resting on 
the top of the other. Thus the trough could contain 100,000 eggs as 
its full capacity. The troughs will carry this number up to the time 
of hatching by placing the trays lower at one end than the other, as 
previously described. 

When the hatching stage arrives, two trays of 12,500 eggs each are 
as many as should be left in one trough ; with this number, by using the 
horizontal sliding- screen in the upper end, there is but little danger of 
the alevins congregating and smothering in any part of the trough. If 
it is necessary to hatch a much larger number than this in one trough, 
the sliding-screen is so arranged that the water falls well up against 
the end of the trough. This is done by raising the screen and turning 
it back against the reservoir, or by putting in a wedge shaped block for 
the water to fall upon, turning the thin side of the block toward the 
upper end of the trough. Fifty thousand trout have been hatched in 
one trough prepared in this way without loss from suffocation, but it is 
not advisable to hatch such a large number together. 

The amount of water necessary for hatching and rearing depends 
upon the temperature and the manner in which the water is applied. 
The water should receive as much aeration as possible before entering 
the compartments containing the fish and eggs. At Wytheville, where 
there is an even temperature of water of 53° in the hatchery, about the 
following quantities are used in the troughs containing fish and eggs : 

100,000 eggs during incubation, 12| gallons per minute. 
100,000 fish hatching to time of feeding, 30 gallons per minute. 
100,000 fish from 1 to 4 months old, 50 gallons per minute. 
100,000 fish 4 to 6 months old, 100 gallons per minute. 
100,000 fish from 6 to 12 months old, 200 gallons per minute. 



80 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 

These amounts are ample, and probably even half would suffice if it 
were necessary to economize in the use of water. In rearing-ponds 
more water is required, as the circulation is not so good and the out- 
door exposure causes the temperature to rise. If water is plentiful, 
double the amounts stated would be advisable for pond-culture. 

During the last two seasons at Wytheville 80 to 85 per cent of the 
eggs taken produced fish, of which about 70 per cent were raised to 
three months old and 55 per cent to yearling fish. The loss in eggs 
was almost entirely due to failure in impregnation, very few being lost 
from other causes. 

CARE OF EGGS AND FRY. 

After the eggs are placed on the trays, the only attention necessary 
until the hatching begins is to keep them clean; the dead eggs, which 
may be known by their turning white, must be picked out at least once 
each day. After the eye-spot can be plainly seen it is well to run a 
feather through the eggs for the purpose of changing their position 
on the trays, and to disclose any foreign matter or dead eggs that 
may be hidden underneath. The greatest care should be exercised in 
handling the eggs at any time, particularly from the first or second day 
after collection up to the appearance of the eye-spot, and then only when 
absolutely necessary. During this period, the eggs are very delicate, 
and even passing a feather through them may cause a heavy loss. 

The time required for hatching depends mainly upon the temperature 
of the water. Eainbow trout eggs will hatch in water at 50° in from 42 
to 45 days, each degree colder taking 5 days longer, and each degree 
warmer 5 days less ; the difference increases as the temperature falls 
and diminishes as it rises. 

After the fry hatch they require but little attention until the umbil- 
ical sac is absorbed and the time for feeding arrives. They are exam- 
ined each day, and the dead fish and decayed matter removed from 
the troughs, which are kept perfectly clean, and if possible provided 
with a thin layer of coarse white sand on the bottom, to keep the fish 
in healthy condition. As the fish grow they should be thinned out in 
the troughs, from time to time, as their size may require. When they 
first begin to feed, 12,000 to 15,000 fish to the trough are not too many; 
but by the time they get to be 1£ to 1£ inches long they must be divided 
into lots of 8,000 to 10,000 to each trough ; while with fish averaging 3 
inches in length, 3,000 to 4,000 are as many as one trough will accom- 
modate. It is advisable to give as much room as is practicable. 

REARING-PONDS. 

Ponds for rearing trout are from 8 to 12 feet wide, and of any desired 
length up to 60 feet, which, for convenience in drawing them off and 
in feeding the fish, is about the extreme limit. The size, shape, and 
arrangement of the ponds must depend upon the ground on which 
they are to be constructed, If practicable, it is best to build them on a 



Report U. S. F. C. 1897. (To face page 81.) 



Plate 25. 




OS 

O W fa 

o 






<J a 



MANUAL OF FISH-CULTURE. 81 

hillside, one above the other, with earth and piling embankments on 
the lower sides and at the ends. A pond of this kind is shown in 
plate 25, and is the one here described. Various materials may be used 
for damming the water. The embankments may be made altogether 
of earth or lined with stone, brick, cement, or timber, according to 
circumstances. Where the ground is of a porous or loose formation it 
is necessary to use piling or cement for the inside of the embankments 
and possibly cement for the bottoms, but earth bottoms are best where 
the nature of the ground permits. The water enters the pond at one 
end and discharges from the lowest opposite corner. The bottom is 
graded as shown in the cross-section, plate 25, with a slope toward the 
outlet, so that when all the water is drawn out the fish are led into the 
receiving- trough (C), the top of which is flush with the earth bottom in 
that part of the pond. 

The outlet for the water is an L-shaped pipe, shown at F, and is 
placed in the corner of the pond, the long end passing through the 
piling and underneath the pond embankment; the short end, called 
the standpipe, stands close to the inside corner of the pond, in an 
upright position. The standpipe has two or more holes cut through 
(G) on the side next to the receiving-trough, to let the water pass out 
in drawing down the pond. The size of these holes is in proportion to 
the size of the standpipe, which, in turn, is governed by the size of the 
pond. The holes may have blocks of suitable size tacked over them to 
allow the pond to fill with water, or, what is more convenient, covered 
with blocks arranged to slip down in grooves, one block resting on the 
other. Surrounding the standpipe is a crib, the front of which is 15 
inches or more from the pipe and contains an opening for a guard - 
screen, which is 14 to 16 inches wide and made with copper or galva- 
nized wire cloth, the size of the mesh depending on the size of the fish 
in the pond. In the bottom of the pond is a receiving-trough (C) for the 
fish, built in proportion to the size of the pond; 10 feet long, 1G inches 
wide, and 6 inches deep is a satisfactory size for a pond like the one 
described. This trough extends to and connects with the standpipe, 
and the guard-screen is arranged to fit down on the inside. Every 
part is made secure, to prevent fish from escaping when drawing off the 
water. The sup ply- trough or pipe is arranged to keep the fish from 
jumping into it from the pond, as shown at A. 

STOCKING THE HEARING-PONDS. 

The rearing-ponds at Wytheville are stocked gradually, 500 to 1,000 
fish being placed in the pond and trained to take food before more are 
added, as that number can generally find enough natural food to sub- 
sist upon until they learn to take artificial food. When they have been 
accustomed to hand-feeding another 1,000 fish are added, and in about 
ten days 2,000 more, this practice being continued until the pond is 
stocked with the desired number. When fish are first released in ponds 

F. C. R. 1897 6 



82 REPORT OF COMMISSIONER OP PISH AND FISHERIES. 

they are wild and run away from the food given them ; hence the neces- 
sity of teaching a few fish to eat before more are added. The number 
of fish that a pond of a given size can support depends upon the amount 
of water and shade and the temperature of the former. Ten thousand 
fish are ample for a pond 10 by 50 feet, with water deepening from 3 
inches to 3 feet. 

POOD FOR PRY. 

Beef or sheep liver, ground or chopped to a pulp, seems to be the 
most satisfactory artificial food for young trout. Fresh, hard-boiled 
eggs, grated flue, are good, but expensive. Efforts have been made to 
produce a natural or living food, such as insect larvae and small crus- 
taceans, and this may yet be accomplished for late spring and summer 
feeding, but for feeding the fry during the first three or four months of 
their lives, which is in the winter season, there is nothing better than 
liver. Shad and herring roe, put up in sealed tin cans, have been used 
to a limited extent with satisfactory results, and it is believed that they 
will furnish a wholesome and natural diet. 

The manner of feeding young fry is very important, as the losses from 
improper feeding are greater than from all other causes combined. If 
there is undue haste the water becomes polluted, or the food is so 
distributed that some fish are prevented from getting their proper share. 
Polluted water is very injurious to the young fish, being apt to produce 
inflammation of the gills and a slimy, itching condition of the skin, 
which often causes heavy mortality. 

The fry are ready to take food as soon as the sac is absorbed, the 
time required for this depending upon the growth of the fish, which is 
governed by the temperature of the water. Where the temperature is 
regular at 53° they will take food in about 30 days after hatching, and 
the time to commence feeding may be closely determined by watching 
the movements of the fish. Before the sac is entirely absorbed they 
will begin to break up the school on the bottom of the trough and 
scatter through the water, rising higher and higher from the bottom 
each day, until they can balance themselves gracefully in a horizontal 
position, all heading against the current and swimming well up in the 
water. By dropping some small bits of cork or the nap from red flannel 
on the surface of the water it can be determined if they are ready for 
food; if they strike at the pieces as the current carries them down it 
is evident they are hungry. 

The liver is prepared by chopping it very fine and, if necessary, 
mixing it with water, in order that it may be distributed evenly. It 
should be given to the fish by dipping a feather into the liver and 
gently skimming it over the surface of the water. After the fish grow 
to be 1^ to 1£ inches long they begin to take up the food that settles 
on the bottom of the trough; it is then not necessary to mix the food 
with water, and it can be given by hand. The young fry are fed five 
or six times a day and the food given slowly and sparingly. After they 



MANUAL OF FISH-CULTUEE. 83 

learn to take their food from the bottom of the trough it is necessary 
to feed them only three times daily, but more food must be given at 
each meal. 

FOOD OF ADULT FISH AND YEARLING-S. 

In domestication the rainbow trout is preferably fed upon a meat 
diet altogether, if it can be had plentifully and sufficiently cheap; 
otherwise a mixture of liver and mush may be used advantageously. 
The mush is made by stirring wheat shorts or middlings in boiling 
water until the mixture becomes thick; it will keep for several days, 
even in warm weather, if put in a cool place. The liver is ground 
or chopped fine and mixed thoroughly with the mush in any desired 
proportion up to four fifths of the whole, but it is better to mix 
only as needed. This mixture has been used satisfactorily for many 
years. 

A meat-chopper may be obtained for grinding liver which will do the 
work in an excellent manner, leaving no strings or gristly chunks to 
choke the fish. There are several sizes of the machine made, with extra 
perforated plates having different- sized holes, from one-twelfth to one- 
fourth of an inch in diameter, so that the meat may be prepared coarse 
or fine, to suit the size of the fish to be fed. For small fry it is neces- 
sary to use the plate having the smallest holes and to grind the food 
over several times until fine enough to use. 

The practice of throwing food into the pond in handfuls causes the 
fish to come together in great numbers and in a violent manner; and 
struggling with open mouths to get a bite of the food, they often hurt 
each other, injure one another's eyes, sometimes even plucking them 
from the sockets. This is probably one of the main causes of blindness 
among pond-fed fish. 

The most approved method of feeding is to walk along the pond its 
entire length to the upper end (the fish will soon learn to follow to that 
point), then scatter a handful of food along the surface of the pond so 
that it will fall to pieces. The fish follow and take up what has been 
thrown out and then return to watch for the next handful, and the 
operation is repeated until sufficient food is given. This manner of 
feeding induces all the fish to head in the same direction while eating, 
thus reducing the danger of injury. 

The amount of food for a given number of trout depends upon the 
size of the fish and the temperature of the water, as fish will not take 
food as freely in a low temperature as they will in warmer water. 
With water from 50° to 60° a daily ration for 1,000 yearling fish ranging 
from 3 to 5 inches in length is about | of a pound; while for the same 
number, 8 to 12 inches long, about 12 pounds per day are required. 

As the fish increase in size the amount of food should be increased 
proportionately. They are fed twice a day at regular hours, morning 
and evening, giving half of the daily allowance each time. This keeps 
them in a thrifty and growing condition. 



84 



REPORT OF COMMISSIONER OF FISH AND FISHERIES. 







Cross-section through Box after it has been packed and closed. 



PACKING EGGS FOR SHIPMENT. 

In packing trout eggs for shipment they are usually placed on trays 
and packed in wet moss and the eggs divided into from five to ten equal 
parts, according to the size of the shipment, using trays of suitable 
size to hold each part. If 30,000 eggs are to be shipped, ten trays are 
used large enough to contain 3,000 eggs each ; if 15,000 eggs, ten trays 




Egg- tray 



B. Foundation-board. 



containing 1,500 eggs each; 10,000 eggs, eight trays of 1,250 each, etc., 
and if over 30,000 eggs are to be shipped the shipment is made in 
more than one lot. In a package of more than ten trays, especially if 
the trays are large, the eggs on the lower trays are liable to be crushed 



MANUAL OF FISH-CULTURE. 



85 




C. Ice-hop2)er. 



by the weight above, and if less than five trays are used in a shipment 
the package is liable to become dry, and the eggs reach their destina- 
tion either dead or in a shriveled condition. 

The frames of the trays are made of light, soft wood dressed to f by 
£ of an inch, with a soft canton-flannel bottom tightly stretched and 
well tacked on. The trays 
are made large enough to 
contain their proportion 
of the eggs, with an allow- 
ance of f of an inch be- 
tween the eggs and the 
frame of the tray . A foun- 
dation-board (B) is made 
with the same outside di- 
mensions as the tray, with 
a strip nailed around the 
edge on the upper side to 
form a cushion of moss 
for the bottom tray. A 
hopper for ice (C) is used 
on the top tray. The out- 
side case (E) is made 7 to 
8 inches larger on the 
sides (iuside measure) 
and 5 inches deeper than 
the outside dimensions of 
all the trays after they 
are cleated together, in- 
cluding the hopper and 
the foundation-board, as 
shown at D. 

The trays having been 
prepared, the eggs are se- 
lected, those being taken 
which show eye-spots and 
are not too old to reach 
their destination before 
the time for hatching. 
Allowance is made for 
changes in temperature 
on the road which would 
cause them to hatch too 
soon. 

The eggs are taken from the hatching-trays in pans, well cleaned of 
all sediment, and given a slight concussion by allowing water to fall on 
them from a small spout or sprinkling pot, which causes the dead and 
unfertilized eggs to turn white, when they are carefully removed. The 




D. Egg-trays packed and cleated. 



86 



REPORT OF COMMISSIONER OF FISH AND FISHERIES. 



eggs are then accurately weighed or measured (1 ounce may be weighed 
and counted, or the eggs for one tray counted and then weighed) and 
the required number placed in a single layer in the middle of the tray, 
leaving an empty space all round next to the frame. 

The trays are then placed one above the other on the foundation- 
board, after each is covered with a piece of mosquito netting, which 
should be at least 2 inches larger each way than the tray, and the 




E. Outside case. 



tray is filled with wet moss, the part immediately over the eggs in a 
loose manner, the empty space around the eggs packed tight. This 
gives support to the next tray above and prevents the eggs from com- 
ing in contact with the wood and becoming dry and shriveled. 

After all the trays are thus arranged the hopper is placed on top and 
the whole cleated together, as shown at D. They are then ready to be 
placed in the box or outside case (E). Dry sphagnum moss is placed 



MANUAL OF FISH-CULTURE. 87 

in the bottom of the box to a depth of about 3 inches and the crate 
of trays placed as near the center of the box as possible. The sides 
are well packed to hold it firmly in position, and when the top of the 
hopper is reached with the packing it is well filled with ice, the remain- 
ing space in the box being filled with moss. Wet moss or wet packing 
of any kind should never be used for the cushion around the egg-crate, 
as it does not preserve an even temperature and is liable to freeze solid 
if exposed to a low temperature in transit. A cross- section of the 
box thus packed is shown on page 84. 

The box containing the eggs should be provided with handles to 
facilitate moving during transportation, in order that the liability to 
injury from jarring or concussion may be reduced. For a long journey 
the lid of the box is provided with hinges and hasp and staple, so that 
the ice may be easily renewed. Eggs packed as described above have 
been shipped with safety to all parts of the United States and to for- 
eign countries. 

DISEASES OF FRY AND ADULTS. 

The most common diseases of trout fry are the inflammation of their 
gills and a slimy skin disease, which may be caused by impure water; 
the food itself may produce it, especially if stale liver is used, but it 
generally follows fouling of the water while feeding. By watching 
the movements of the fish, the symptoms of disease can generally be 
detected before it reaches an alarming stage. If the gills are affected 
the fish will usually swim high in the water in an uneasy, restless man- 
ner, as if gasping for breath, and when this is observed the gills must 
be examined to see if they are becoming inflamed and swollen. If a 
skin disease is attacking the fish, they generally indicate it by rubbing 
themselves on the bottom of the trough or against anything that may 
be convenient, or by diving down and giving themselves a quick, twist- 
ing motion against the bottom of the trough. If the progress of dis- 
ease is not promptly checked, it will soon reach a stage where nothing 
can be done, and the fish grow weaker every day until they begin to 
die in alarming numbers. One of the best remedies for both diseases 
is salt sprinkled through the water after the ponds are drawn low, and 
for a bad case of skin disease a half pint of salt for every gallon of water 
in the trough is used, or about that proportion. The fish should be 
watched closely and allowed to remain in the salt water until they 
become restless and begin to turn on their sides. Then, as fresh water 
is turned on and the trough fills, a slime will arise and float on top of 
the water, like a white scum. Coarse sand should be kept in the trough 
for the fish to rub themselves against. Salt is also good for the dis- 
eased gills and will free them from adhering sediment. 

Fungus, "blue swelling," and other diseased conditions sometimes 
occur, but the most serious diseases of the fry are those just described. 
Parasites sometimes attack the fish, but if the water is pure and the 
fish in a healthy condition, they are not troublesome. To keep the fish 



88 REPORT OF COMMISSIONER OP PISH AND FISHERIES. 

that are raised in troughs and tanks in a healthy state, it is well to give 
them a salt bath occasionally, and a small quantity of salt in their food 
will at times do them good. A little sediment from the reservoir, or 
such as collects on stones in the streams, is beneficial to fish if mixed 
with their food. It seems proper that they should have something of 
this nature, since all or nearly all of their natural food contains more 
or less sediment of the kind, 

A very serious disease among adult rainbow trout shows the follow- 
ing symptoms: The afflicted fish refuse to take food, and very dark 
spots, from J to 1 inch in diameter, appear on different parts of the body, 
varying in number from two or three up to twenty or thirty on each 
fish affected, a light spot about the size of a green pea appearing on 
the head immediately over the brain. The fish become restless and 
seek the shallow water in the corners of the pond, hiding among the 
plants, and begin to die within twenty- four hours from the time the dis- 
ease is noticeable. They jump and dart around in the water in a 
frightened manner, settling back on their tails and sinking to the 
bottom of the pond in their last struggles. This disease made its 
appearance at Wytheville in December, 1895; it was first observed 
among a lot of 637 yearling Yon Behr or brown trout that had been 
delivered at the station on November 29. The first sign of the disease 
was noted about the 5th of December, and by the 12th of the month 
455 of the 637 fish were dead. 

These fish were in the nursery during the first stages of the dis- 
ease. The water in which they were held passed from them through an 
empty pond into a second one containing about 1,000 large rainbow 
trout that had recently been stripped of their spawn. On the morning 
of December 23 the disease made its appearance among the latter, and 
by 4 o'clock in the afternoon of the same day 56 of them had died. 
Salt was applied and the water in the pond was drawn down to about 
300 gallons, and 150 pounds of common salt were sprinkled evenly 
through it. The fish were allowed to remain in this brine about 15 
minutes, when they showed signs of weakening by turning on their 
sides ; then fresh water was turned on freely. Good results were at 
once noticeable, the fish became quiet and appeared to rest more easily, 
and steadily improved, another application not being necessary. The 
final result was that 70 per cent of the adult rainbow trout that had 
been treated with salt were saved, while of the yearling brown trout 
that were not thus treated nearly 71£ per cent died. 

Foul ponds cause disease, and if the fish become sick from this reason, 
they must be removed to a clean pond at once and given a saltand- 
clay bath, which is applied as follows: While the salt bath, before 
described, is being given, 2 or 3 bushels of clay are placed in the 
reservoir or supply-trough, and when the fresh water is turned on after 
salting, the reservoir is flushed for 30 minutes with roily water from the 
clay, and after the latter is washed away an increased amount of fresh 
water is turned on for ten days or more. 



MANUAL OF FISH-CULTURE. 89 

Adult fish are very liable to be affected with fungus, which generally 
appears after a bruise or hurt, or when the fish are in an emaciated 
condition. If the trouble results from au injury, it can often be cured 
before it spreads to the sound flesh, but if fungus spreads like a slimy 
web all over the fish, it is fatal. Fish must be handled very carefully 
daring the spawning season to prevent scarifying the body in any way, 
as they are especially susceptible to fungus at that period. Should it 
occur, the fish must be caught at once, rubbed with salt on the affected 
part, and then released in a pond or tank by itself, where it can be 
caught for further treatment in a day or two, while those affected all 
over the body should be killed and thrown out at once. 

"Glassy eggs" may be the result of overretention of the eggs on the 
part of the parent fish. If the eggs are not delivered within a reason- 
able length of time, say from 36 to 48 hours after they fall from the 
ovaries into the abdomen, they are surrounded with a thin watery fluid, 
having a glassy appearance, which if allowed to come in contact with 
water will change to a milky white, and the eggs absorbing this fluid 
become hard and " glassy," after which fecundation is impossible. 
Many thousand eggs have been lost annually on this account, and many 
brood fish lost or rendered worthless from the same cause. The fish in 
captivity will not spawn of their own accord unless they have access 
to gravel or earth in which to make nests. If attention is not given to 
the spawning fish and their eggs taken when ripe, they soon become 
very dark in color, the abdomen swells, and sometimes the head will 
enlarge, causing the eyes to protrude. Under these conditions the fish 
will die in a few days, but with free and easy access to the raceway 
they will not often be thus affected. 



Report U. S. F. C. 1897. (To face page 91.) 



Plate 26. 




THE BROOK TROUT. 



DESCRIPTION OF THE FISH. 

The brook trout or speckled trout (Salvelinus fontinalis) is one of the 
most beautiful, active, and widely distributed of the American trouts. 
It prefers clear, cold, rapid streams, and belongs to that group of trout 
known as charrs, characterized by the presence of round crimson spots 
on the sides of the body. Other members of this class are the saibling 
or charr (Salvelinus alpinus) of Europe and Greenland; the Sunapee 
trout (S. alpinus aureolus), found in parts of New Hampshire and 
Maine; the blueback trout (S. oquassa) of the Eangeley Lakes in Maine, 
and the Dolly Varden trout, red-spotted trout, or bull trout (8. malma) 
of the Pacific States and Alaska. The lake trout also belongs in this 
group. 

The general form of the brook trout's body varies considerably, some- 
times being elongated and sometimes rather short, but the usual depth 
is about one-fourth or one-fifth of the length. The head is large and 
blunt, and is contained 4£ times in the body length. The large terminal 
mouth is provided with teeth on the jaws, tongue, and palate bones, 
and also with a small patch on the vomer. The eye is placed high in 
the head-; its diameter is about one sixth the length of head. The gill- 
rakers on the first arch number about 17, of which 11 are on the lower 
arm. The scales are very small and numerous; about 230 are in the 
lengthwise series, and 35 above and 35 below the lateral line. The 
dorsal and anal rays are 10 and 9, respectively. The tail is square or 
slightly lunate in the adult, forked in the young. 

There is considerable variation in the color of the brook trout, 
dependent on local conditions, sex, and age. The head, back, and 
sides of the body, dorsal and caudal fins are of a grayish or greenish 
color; the back, head, dorsal, and base of caudal are mottled with dark 
green or black. In the male there is a reddish band along side of belly. 
Along the middle of the side there are numerous round light-red spots 
surrounded by whitish or light-brownish circular areas. The lower fins 
are dusky, with a pale or cream-color anterior border bounded by a 
black streak; remainder of fin often red in breeding males. 

The brook trout may be distinguished from the other charrs by the 
dark-brown or black marblings on the back and the general absence of 
spots on the back. 

91 



92 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 

FOOD, SIZE, ETC. 

The brook trout has a voracious appetite and takes advantage of 
every opportunity to satisfy it except in the spawning season, when it 
takes no food at all. It is strictly a carnivorous fish, its food consisting 
chiefly of Crustacea, mollusca, and various forms of insects and worms. 
When pressed with hunger it does not hesitate to devour its own kind. 

The size of these fish varies in different localities, usually in propor- 
tion to the abundance of natural food and to the size of the body of 
water in which they are found. They seldom, however, exceed 2 pounds. 
The Au Sable Eiver trout will rarely run as large as 2| to 3 pounds, but 
in other rivers of Michigan larger examples are occasionally found. In 
southern New York they seldom weigh over 2 pounds, while in the 
Eangeley Lakes, of Maine, they have been caught weighing 10 pounds. 
The rate of growth also varies with the surrounding conditions and is 
more rapid in water of higher temperature and with a plentiful supply 
of food. Under favorable circumstances an average growth for the 
first year is from f to 1 ounce, in two years 8 to 10 ounces, in three years 
about 1 pound. 

While not of any considerable commercial importance, the brook 
trout is highly esteemed as a table delicacy on account of the flavor 
and quality of its flesh, and, as it is very game, it is much sought after 
by sportsmen. Those from clear, swiftly flowing streams do not grow 
so large as those found in quiet and deeper waters, but are superior in 
quality and appearance. 

RANGE, SPAWNING-, ETC. 

The natural range of the brook trout in the United States is from 
Maine to Georgia and westward through the Great Lakes region to 
Minnesota, and in Canada from Labrador to the Saskatchewan. Owing 
to its hardy nature and ability to adapt itself to new surroundings, it 
may be successfully transplanted into suitable streams, and has been 
extensively introduced into waters to which it was not native, in Mich- 
igan, Wisconsin, and Minnesota, many of the waters of the Eocky 
Mountains and the Pacific Coast, the Eastern States, and the creeks 
and rivers of the Alleghany range of mountains. With the possible 
exceptions of the rainbow trout and steelhead it is the hardiest mem- 
ber of the salmon family and will make a brave struggle for existence 
even with adverse surroundings. All streams can not be successfully 
stocked with this species; the temperature of the water must not be too 
high nor the flow too sluggish, although an unfavorable temperature is 
no serious obstacle if the speed of the current is great enough to insure 
a sufficient aeration of the water, or if there are creeks fed by springs 
flowing into the main stream to which the fish can run. The best 
streams are those with a gravelly bottom, clear shallow water, and a 
steady current, and waters to be stocked must contain a sufficient 
amount of natural food and suitable places for spawning. 



Report U. S. F. C. 1897. (To face page 93.) 



Plate 27. 




MANUAL OF FISH-CULTUEE. 93 

The Michigan streams exemplify the practical results attained in 
the introduction of brook trout in new waters. The Au Sable Eiver 
was long thought to be especially adapted for this species, but it 
abounded with grayling, and until this beautiful fish began to disappear 
no movement was made toward introducing the brook trout. The 
lumber interests of that section made it necessary to use the river for 
conveying logs to various points downstream, and, as the log-driving 
could be done only during the spring freshets, it came just at the time 
when the grayling were on their spawning-beds. They were driven 
away and the beds destroyed by the plowing of logs through the 
river bottom each year, till the fish gradually began to disappear. 
The brook trout was suggested as the proper substitute, because its 
spawning season is in the autumn when the river is undisturbed, and 
the Michigan Fish Commission began the work by planting 20,000 fry 
in the year 1885. Though additional plants were made from time to 
time, both by the Michigan and United States Commissions, no results 
were observed for some years, and it was thought that the work had 
been a failure. But the natural instinct of the fish had caused them 
to push from the main river into the small tributaries, where they 
multiplied and grew during these years till they finally crowded down 
into the river itself. Here they found as suitable a home as in the 
small streams, and their numbers gradually increased till now the 
stream is completely stocked. 

In the autumn of 1895 a camp was established for the United States 
Fish Commission 9 miles below the village of Grayling for the purpose 
of taking spawn from wild fish. The work was confined to rod-and-line 
fishing until the spawning season opened, when it was found necessary 
to adopt some other plan, as at this time the trout refuse to feed. 
During the five weeks, in which the rod was used exclusively, 3,000 
spawning fish were taken. A small seine was then used for capturing 
the fish, by hauling it at right angles to the current of the river, directly 
across the spawning-beds, which thickly dotted the river bottom in 
some places. By this method a tubful of trout at one haul was often 
taken, and during the period the fish were running between 8,000 
and 10,000 were obtained. This illustrates the abundance in which 
this species is found in a river to which it has been transplanted. A 
conservative estimate would place the number of trout taken from 
this stream in the season of 1895 at 100,000, perhaps 25 per cent being 
rainbow trout. Other waters of the State have been successfully 
stocked, so that the northern half of lower Michigan now contains a 
network of trout streams, made by introducing this fish into waters 
where it was not indigenous. 

In its native haunts, whether in lake or stream, the brook trout is 
usually found in the same clear, cold, spring water, and prefers brooks 
or streams flowing swiftly over gravelly bottoms. It pushes from the 
rivers into the small streams, seeking the headwaters, searching out 



94 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 

the deep pools and eddies where it can lie concealed beneath the shelter 
of grassy banks or logs, and see without being seen. Under artificial 
conditions it endures higher temperature than in its native waters, 
where it is seldom found in water warmer than 60° to 65°. It thrives 
at much higher temperature in swift, well-aerated streams than in 
sluggish waters. 

The brook trout spawns in autumn during the falling of the water 
temperature. The season, which usually lasts about two months, begins 
earlier in northern latitudes, in the Lake Superior region in September 
or even August, while in New York, New England, and lower Michigan 
it commences about the middle of October. 

As the spawning time approaches the fish push up toward the 
shallower waters where the female selects a spot near the bank of the 
stream and prepares her nest by washing out the sand with her tail 
and pushing aside the gravel with her nose. After forming a slightly 
concave depression she deposits a part of her eggs on the newly cleansed 
gravel, and the male — which up to this time has been playfully swim- 
ming around the nest — emits milt upon them almost simultaneously. 
The female then covers the eggs with the loose gravel. The spawning, 
impregnating, and covering are repeated continuously until the eggs 
are all laid. After the spawning-ground is once selected it is hard to 
drive the fish away, the female especially returning to the same spot at 
the earliest opportunity. A female has been taken from her nest and 
marked and then returned to the water a mile down the stream, and 
the next morning was found on the same bed as though nothing had 
happened. 

The eggs vary in size, but are usually one-sixth of an inch in 
diameter. The number yielded by one fish depends on its size and age, 
yearlings usually producing from 150 to 250, two-year-olds 350 to 500, 
and older fish 500 to 1,500. The time necessary for developing the eggs 
is dependent on the temperature of the water, varying from about 125 
days in water at 37° F. to about 50 days in water at 50° F. 

TROUT-CULTURE IN AMERICA. 

The first attempt at artificial trout-culture in America was made in 
Ohio in 1853 and marked success attended the efforts. Further satis- 
factory trials were made in 1855 and 1859 in Connecticut and New York, 
and in 1864 a hatchery was established in New York which became a 
practical success in carrying on the work on a large scale. Somewhat 
later the work was taken up by the State and United States govern- 
ments and is now very extensively carried on in all parts of the United 
States. 

The methods described in the following pages are those which have 
been found advantageous at the North ville station, and are there pur- 
sued. In addition to the eggs obtained from brood fish held in ponds 
at the hatchery a field station for collecting eggs from wild trout is 
operated on the Au Sable Biver. 






Report U S. F. C. 1897 (To face page 95.) 



Plate 28. 




MANUAL OF FISH-CULTURE. 95 

THE FIELD STATION. 

For the egg-collecting station a point was selected, on a tributary of 
the An Sable, flowing about 1,000 gallons per minute, near where it 
empties into the river. A dam was thrown across the stream and 100 
feet above a screen was built to prevent the fish from escaping in that 
direction. The dam is simply constructed by banking up mud, sand, 
aud turf, and has a frame sluiceway 3 feet long, 2 feet wide, and 2 feet 
deep. In the sluiceway is inserted a double screen of J-inch mesh wire 
netting, two screens being necessary to keep the overflow clear and 
reduce as low as possible any loss of fish through this outlet. The 
inclosure accommodates about 10,000 fish. For holding the eggs two 
pairs of troughs are placed on standards driven into the bed of the 
stream, with a passage between them wide enough to admit a man. 
Fish are obtained with rod and line, until they begin to run from the 
deep pools upon the spawning-grounds, when much better results are 
obtained with nets. With an ordinary seine at the approach of the 
spawning season, the fish can be taken in large numbers from their 
spawning beds. As the season advances and too many fish are caught 
that have already spawned, operations are suspended. 

The water is received through two 1-inch orifices in a bulkhead about 
9 feet long, situated at the head of these troughs and fed by a roughly- 
constructed raceway leading from a small spring about 6 rods distant 
on the hillside. The water from each of the openings feeds two 
troughs, so placed that the lower end of the upper one rests upon the 
head of the other, thus creating a fall of nearly the height of the 
troughs. Each trough is 11 feet long, 5 inches deep, and consists of a 
double row of boxes, each box 17 inches long, 15 inches broad, and 2 
inches deep, giving a capacity of from 8,000 to 10,000 eggs. 

As soon as ripe fish are found among those caught on the spawning- 
beds, the pond is hauled with a seine and the fish are looked over twice 
a week until all the eggs are taken. When the season is fairly opened 
the spawn may be taken from most of the fish immediately after they 
are caught, thus obviatiDg the difficulty of transferring them from the 
point of capture to the pond, in some cases a distance of 3 or 4 miles. 

TAKING THE SPAWN — DRY PROCESS. 

A good spawn-taker can tell at a glance if a female is ripe, and only 
in such condition should an attempt be made to take her eggs. After 
the ripe males and females are placed in separate tubs or buckets, the 
spawn-taker is ready to take the eggs, the implements necessary being 
a feather and an ordinary milk-pan coated with asphaltum paint on the 
mside to prevent rust. The pan is first dipped in water and allowed 
to drain, leaving only the water that clings to the inside. Taking a 
female from the tub she is held as quietly as possible till all struggles 
cease, and then pressing gently with the thumb and forefinger a little 
above the ventral fins, the hand is passed down the belly to the oviduct, 



96 EEPORT OF COMMISSIONER OF FISH AND FISHERIES. 

and the operation repeated till all the eggs are extruded. The eggs 
are immediately impregnated with milt, which is obtained from the male 
in similar manner, except that more force is necessary and the pressure 
is made at a point about midway between the ventral and anal fins. 

The contents of the pan are next lightly stirred with a feather to 
insure impregnation of all the eggs possible. They now present a 
milky appearance and are washed in as many changes of water as is 
necessary to thoroughly cleanse them from the milt and other refuse, 
when the pan, left half filled with fresh water, is placed in running 
water to keep the eggs at a low temperature. After from 30 to 60 min- 
utes, according to the temperature of the water, the separation of the 
eggs ensues. 

In the work on the Au Sable Eiver, the eggs, after separating, are 
laid on gravel placed £ inch deep in the boxes of the troughs. Here they 
remain till the eye-spots begin to appear, when they are prepared for 
shipment. During this interval of about thirty days the principal care 
consists in sorting out bad eggs, and, with a feather, gently changing 
the position of good ones to prevent sediment from collecting on them. 

SHIPPING GREEN EGGS. 

Green eggs can be safely moved at any time up to and including the 
eighth day. They are shipped from the field station to the hatchery in 
cubical boxes constructed from -J-inch pine lumber, just large enough 
to admit, with a surrounding air-space of ^ inch, 19 canton-flannel trays, 
18 inches square on the inside, the frames of which are made from |-inch 
square white pine. The eggs are drawn by means of a siphon from the 
gravel boxes into a tub or bucket which has been half filled with water 
to prevent them from injury. Using a graduated dipper for the pur- 
pose of ascertaining approximately the number of eggs necessary to 
make them about two deep on the tray, the packer pours them upon 
the flannel and spreads them as evenly as possible with a feather. The 
tray is then placed in the box and the operation repeated until eighteen 
trays are filled with eggs. The nineteenth, or top tray, is usually left 
empty, but if the weather is very warm it is filled with fine ice. The 
cover is then fastened down, the box marked, and the eggs are ready 
for shipment to the hatchery. 

THE HATCHING APPARATUS. 

After a period of about thirty days on the gravel, the eggs are taken 
up and placed in the Clark hatching-box, for here they may be held 
without any appreciable loss through the escape of fish when hatching. 
This apparatus as used at North ville is arranged as follows : A tank 15 
feet long, with a partition running its entire length, is so placed that 
its lower end rests upon the upper end of a similar one 13 feet long, 
which differs from the upper one only in that it contains two boxes less. 
Nine partitions, placed crosswise of the tank, form, with the lengthwise 
partitions, a double row of eight compartments, each of which is 19£ 



Report U. S. F. C. 1897. (To face page 97.) 



Plate 29. 




MANUAL OF FISH-CULTURE, 97 

inches long and 15£ inches wide, and is provided with a waste-water 
channel or sluiceway leading into the next compartment. In these 
compartments are placed the hatching-boxes proper. 

The Clark box is 18 inches long, 14 inches wide, and 9J inches deep, 
and is made from f -inch dressed whitewood lumber. On its under side 
the box is provided with feet, 1^ inches square and § inch thick, to allow 
a free circulation of water under it and to prevent it from resting upon 
any sediment or refuse that may be deposited on the bottom of the 
tank ; and on the inside in each bottom corner is fastened a block, § inch 
thick by 1£ inches square, to support the trays. Five circular openings, 
£ inch in diameter, permit the -escape of water from the box. A slot is 
cut in one end of the box so that water from the compartment above 
can not flow into the one below without falling into and passing through 
this box. Upon the feet or risers inside the box rest 9 trays, made of 
perforated zinc or fine wire netting, tacked upon a frame 16 inches long 
and 12 inches wide. This frame is made from finch pine, 1^ inches 
wide. The trays are placed one upon the other in the box, the end 
which contains the slot fitting snugly against the upper end of the com- 
partment, in which is fitted a tin overflow. The whole is held in place 
by a crossbar or binder, which fits in f-inch grooves cut in both sides 
of the tank. The binder, resting upon the box, keeps it from rising in 
the water, and is provided with feet so placed as to prevent the trays 
from floating in the box itself. 

Upon the arrival of the green eggs at the hatchery they are trans- 
ferred from the flannel trays to a large galvanized iron pan, and 
thence to the Clark hatching-boxes. The eggs are measured with a 
glass graduate and 5,000 placed upon each tray, the ninth or top tray 
being used only as a cover. The eggs from domesticated brook trout 
measure 350 to 450 per fluid ounce, depending on the age of the fish. 
Eggs from wild trout collected in the Au Sable Eiver measure 450 to 
the fluid ounce. 

CAEE OF THE EGGS. 

At intervals of from three to six days during the period of incuba- 
tion, in order to remove the bad eggs, the trays are taken from the 
boxes and placed in a shallow picking-trough through which a stream 
of not more than 3 gallons per minute is flowing. This trough is only 
wide enough to allow perfect freedom in handling the trays when put- 
ting them into or removing them from it, and only of sufficient depth 
to allow the eggs to be fairly covered. .Nailed to the bottom on each 
side is a £-inch strip, 1£ inches wide, and running the entire length of 
the trough. These strips permit the free passage of water beneath 
the trays, as otherwise the water would flow over the tops and a great 
many eggs would be lost. The bad eggs are removed with a pair of 
tweezers, the'labor of sorting being usually performed by girls, who in 
time become so expert that one girl will often remove 100 bad eggs per 
minute. 

I\ C. E. 1897 7 



98 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 

After the incubation has reached a stage where the fish are begin- 
ning to break their shells, the hatching-box is taken out and reversed, 
the open end being fixed snugly against the lower wall of the compart- 
ment. The closed end of the box being thus placed upstream, the 
water is prevented from entering except through its former exit, the 
holes in the bottom of the box, and is thus forced up through the box, 
with an exit at the top which prevents the sacs of the hatching fish 
from being forced, by pressure from above, down through the screen, 
as would be the case if the box were left in its former position. 

When the process of hatching is nearly completed the trays are 
removed and emptied into a large pan filled with water, where the dead 
shells and other refuse, being of low specific gravity, rise to the top 
and can be easily poured off. This is called washing the fish. The fish 
are then replaced upon the trays and returned to the hatching-boxes, 
where they remain until the food-sac is nearly absorbed, a period of from 
25 to 40 days, according as the temperature varies from 50° to 38° F. 

The young fry, deprived of their food supply by the absorption of 
this sac, must soon be placed where they can get their sustenance else- 
where. They may be planted in waters suitable to their nature, or 
reared for breeding or other purposes at the station. 

PLANTING THE FRY. 

In their natural state, as soon as the weight of the food-sac has 
diminished by absorption enough to permit their rising, the fish begin 
to take food, and by the time the sac is entirely gone they are probably 
taking it regularly. When very young fry are transferred to outside 
waters where there is natural food only, it should be done 8 or 10 days 
before the sac is entirely absorbed, for, if delayed till after the sac dis- 
appears, many will die before they become accustomed to finding food 
in their new home. 

Brook-trout fry are usually transported in ordinary round-shouldered 
cans of 10 gallons capacity, the number of fish per can depending 
entirely upon the distance they are to be carried and the facilities for 
taking care of them en route, such as opportunities for changing the 
water, supplying fresh ice, etc. For a short trip of from 5 to 10 hours 
duration, between 4,000 and 5,000 are carried in each can, but where 
they are to be on the road from 1 to 5 days, it is hardly safe to attempt 
carrying more than 2,500. The United States Fish Commission dis- 
tributes fry by means of its cars, built especially for the purpose, in 
which either running water is kept upon them or fresh air introduced 
into the water to make it life-sustaining. Small shipments are made 
by a special messenger in a baggage car, the railway companies usually 
offering every available opportunity for changing water, etc. The fish, 
upon arrival at the railway point nearest their destination, are carried 
thence by wagon to the stream where they are to be planted, by dis- 
tributing them in small lots in different places where there is shallow 
water and a good bottom. 



MANUAL OF FISH-CULTURE. 99 

REARING- AND FEEDING. 

If the fry are to be reared for breeding, one week before the food-sac 
is absorbed they are changed from the trays to a large pan and removed 
to the rearing-troughs. Gravel should not be used in these troughs, 
as the unconsumed food works down into it and, becoming fungussed 
there, causes a greater spread of disease and increases the labor of 
caring for the fish. 

The time to begin feeding the fry is readily ascertained by trial. If 
they rise to minute particles of food thrown upon the water, they are 
then ready for regular feeding. The time and frequency of feeding 
young fish, the kind of food, and the manner of feeding them, are of the 
greatest importance. Liver gives better results than any artificial 
food, and its preparation is very simple. Beef livers are ground by a 
meat-chopper and then strained through a fine-meshed screen, a thick 
pudding being made by the addition of water. A small portion, only 
such an amount as the fish will readily eat at a time, is spread upon 
the surface of the water with a feather, and they are fed as often as six 
or eight times per day until they become used to the new diet. As 
they grow older the quantity of food may be increased but the fish are 
fed less frequently. At this stage the young fish have such a preca- 
rious hold upon life that too much attention can not be given to their 
care. Not more than 20,000 can be held with success in a feeding or 
rearing trough, and a regular stated supply of water is kept flowing 
through to prevent disease, and the fish are properly thinned out in 
order to prevent loss by suffocation when they increase in size. About 
30 gallons of water per minute are sufficient for 20,000 fry, though this 
quantity is increased as the fish grow stronger and are able to breast a 
heavier current. 

In the spring season, when the water begins to grow warm, the fish 
require more room than the feeding-troughs afford, and it is then nec- 
essary to transfer them to ponds. The Korthville rearing-ponds are 
5 feet by 20 feet, made from 2-inch pine boards and provided with a 
gravel bottom. A pond of this size accommodates from 10,000 to 20,000 
fry till the middle of the summer, when the number is reduced to as 
low as 5,000. It is advisable to place not more than 5,000 in the pond 
at first to avoid the labor of reducing the number of fish at different 
times, and also because crowding into too small a space retards their 
growth. 

At first the fish require coaxing to induce them to eat, as the change 
to their new abode has frightened them, and a great deal of patience is 
necessary in their treatment. They are fed at regular intervals three 
times per day. As their appetites are poor for the first few days, the 
liver will fall to the bottom and foul the pond, if great care is not exer- 
cised, and three fourths of an hour is not too long for feeding 5,000 fry. 
The time occupied in feeding is diminished and the amount of food 
increased according to the judgment of the fish-culturist; but their 
appetites should never be completely satisfied, 



100 REPORT OP COMMISSIONER OP FISH AND FISHERIES. 

By early winter they will have grown to a length of from 3 to 6 inches, 
necessitating a change to a larger pond. The Northville breeding- 
ponds are 20 by 75 feet, and are constructed in the same manner as 
the rearing-ponds. One of these larger ponds accommodates 10,000 
yearlings, 5,000 two-year-olds, and about 3,000 fish from three to five 
years old. By the time the fish are three years old and over, less care 
is required in the preparation of their food, as the liver may be given 
to them in pieces half an inch iu diameter. 

PACKING EYED EGGS FOR. SHIPMENT. 

Eyed eggs prepared for shipment in the following manner have been 
sent from Northville to all parts of the United States with practically 
no loss: The trays upon which the eggs are to be shipped are made 
from the same materials as those upon which green eggs are carried, 
but are usually much smaller. Fewer eggs are placed upon a given 
surface than is the case with green eggs. For example, 10 trays, 12 
inches by 12 inches, will carry 50,000 eggs; 8 trays, 10 inches by 10 
inches, 32,000 eggs; and 5 trays, 8 inches by 8 inches, 12,500 eggs; or 
5,000, 4,000, and 2,500 eggs per tray, respectively. 

The trays are allowed to stand in cold water till thoroughly soaked, 
and are then drained off and taken to the packing-room. After the dead 
eggs have been removed from a box, the trays are taken out, drained, 
and removed to the packing-room. A f-inch wooden frame, made to fit 
the inside of the canton-flannel tray, is then inserted, the eggs are 
carefully brushed with a feather from the wire trays and spread as 
evenly as possible upon the flannel. The eggs have been previously 
measured at the time when they were removed from the gravel to the 
hatching-box, so tire number to be placed upon each tray can be easily 
determined. After the eggs are spread upon the flannel, the inside 
wooden frame is taken out, leaving a § inch margin around the inside 
of the tray. A square of mosquito netting large enough to lap over on 
all sides of the tray is laid upon the eggs and tucked down firmly alo.ng 
the inside. Sphagnum moss is scattered to a depth of about f inch 
upon this netting. The moss is prepared by removing sticks and other 
foreign matter; it is soaked in water a short time and then run tb rough 
a clothes- wringer. In spreading it upon the netting the moss is picked 
apart and made as light and fluffy as possible, to give the eggs plenty of 
oxygen. 

When the required number of flannel trays are packed they are 
placed one upon another and cleated together on all sides, with boards 
at the bottom and top. This crate is usually placed, if possible, where 
the temperature of the air is below freezing, so that the moss may be 
slightly frosted before the crate is put in the shipping-case. 

A case is made large enough to allow a 4-inch space above, below, 
and around all sides of the crate when it is placed in position. Its 
bottom is filled with fine shavings, 4 inches deep, and the crate placed 
upon them as nearly as possible in the center of the case. Shavings 



Report U. S. F. C. 1897. (To face page 101.) 



Plate 30. 





REMOVING GREEN EGGS FROM SHIPPING-TRAYS. NORTHVILLE. 




PACKING EYED EGGS, NORTHVILLE. 



MANUAL OF FISH-CULTURE. 101 

are packed tightly around the crate, a few being thrown in and pounded 
down securely before more are added. This must be well done, as the 
shavings are the only means of preventing a change in the position of 
the crate. The top of the crate is then covered with closely packed 
shavings and the cover of the case screwed on. By means of rope or 
iron handles the case may now be moved about with ease, and is ready 
for shipment. 

REFRIGERATOR BOX FOR SHIPMENTS ABROAD. 

A double box is used for this purpose. The inside one is 2£ inches 
larger on all sides than the crate of trays, and the outside one large 
enough to make a 5-inch space on all sides when the smaller box 
is placed within it. The trays of eggs are prepared as in ordinary 
shipments, and when crated are placed in the smaller box upon a frame 
which is constructed from a £-inch strip, 2^ inches wide, tacked at right 
angles to the inside and bottom of this box. In the chamber thus 
formed between the crate and the box is packed finely chopped ice, an 
exit for the water resulting from its melting being provided by a half 
dozen opeuings in the bottom of the box. This box is now packed 
according to the same plan as that followed with the shipments for a 
short distance. Where there is an opportunity, it is well to have the 
case unpacked en route and new ice added. 

Eggs have been sent in this manner to England, Mexico, New Zea- 
land, Japan, and South America. 

DISEASES. 

Brook-trout fry are subject to diseases and epidemics, and extreme 
measures are often necessary to eradicate these evils. Many experi- 
ments have been made to discover some method of treatment that will 
prevent the introduction of disease. At Northville the troughs are 
Hushed every day for five minutes with an extra supply of water, and 
twice a week they are thoroughly cleansed with a stiff brush or sponge. 
The fry are then treated with a weak solution of salt, which is allowed 
to remain until the fish show signs of discomfort, when the troughs are 
flushed for a few minutes and the water reduced to its regular flow. 
As the fish increase in size they may be thinned out in the trough and 
also at the first indication of disease. 



Report U. S. F. C. 1897. (To face page 103.) 



Plate 31. 




THE LAKE TROUT. 



DESCRIPTION OF THE FISH. 

This handsome species (Gristivomer namayctish), the largest of the 
trouts, is classed with the charrs. It has an elongated body, the length 
being about 4£ times the depth. The head is large, flat above, and about 
as long as the body is deep. The mouth is large; the maxillary bone 
extends beyond the eye and is half the length of the head; the jaws 
have strong teeth. A peculiarity of the vomerine bone distinguishes 
this fish from the genus Salvelinus ; it has a crest provided with teeth 
extending backward from the shaft of the bone. On the hyoid bone the 
teeth are in a cardiform band. The eye, placed near the top of the head, 
is contained about 4£ times in length of head. The caudal fin is well 
forked. Both the dorsal and anal fins contain 9 to 11 rays. In the straight 
lateral line there are about 200 scales. Branchiostegals 11 or 12. 

The coloration is quite variable in fish from different localities. The 
general color is usually dark gray. The body, head, and fins are 
covered with small discrete rounded spots, usually of a pale color, but 
often tinged with reddish. On the back and top of head there are fine 
vermiculations, as in the brook trout. Examples from some lakes of 
Maine and eastern Canada are nearly black, and Alaskan examples 
are often very dark; others are quite pale. 

That variety of the lake trout known as the siscowet {Gristivomer 
namaycush siscowet), found only in deep water in Lake Superior, is 
shorter and paler than the typical fish and has weaker teeth and a shorter 
head ; it is, however, chiefly characterized by an excessive fatness, which 
greatly reduces its food value. 

The present chapter is devoted to trout of the Great Lakes and the 
methods of propagation employed at the station of the United States 
Fish Commission at Northville, Michigan. 

RANGE, FOOD, ETC. 

The lake trout is found throughout the chain of the Great Lakes, and 
the inland lakes of northern ISew Tork, New Hampshire, and Maine; 
the headwaters of Columbia and Fraser Bivers, streams of Vancouver 
Island, and even waters within the Arctic Circle are said to contain 
this species. With the exception of the whitefishes, it is perhaps the 
most numerous food-fish of the Great Lakes, and formerly none exceeded 
it in weight except the sturgeon. Instances are cited by fishermen and 
others of lake trout weighing as high as 125 pounds, and its average 
weight has been given at from 20 to 30 pounds, but of late they are 
rarely found exceeding 18 or 20 pounds. Possibly, if unmolested by 

103 



104 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 

man, they might again reach the enormous weight of early citations, 
their sluggish movements and voracity being conducive to such a result. 

The nature of their environments has a decided influence on the 
characteristics of this species; the temperature of the water, food, and 
character of bottom entirely changing the marking and peculiarities of 
these fish in their various habitats. 

Until recently it was commonly thought that the principal food of the 
lake trout was the young whitefish, and for this reason the fishermen 
of the lakes were generally unfavorable to its artificial propagation. 
The error of that belief, however, is now generally conceded, though 
no doubt quite a number of young whitefish become food for trout 
during each season. But as the habits of the lake trout take it to 
deep water immediately after spawning, while the young whitefish 
remain in shallows, the few which are destroyed in this manner are 
either stragglers from shoal to deep water or taken by trout aimlessly 
wandering from their natural range. The lake trout is an omnivorous 
feeder aud has a ravenous appetite. It greedily devours all fishes 
possessing fins of flexible character, and jackknives, corncobs, and 
other articles equally indigestible have been found in its stomach. 

The spawn and fry of lake trout suffer from the same enemies as the 
young of all fishes, but the mature fish are too formidable for other 
species to prey upon. They are troubled with a few parasites. Oc- 
casionally individuals, very thin in flesh and sickly-looking, known as 
"racers" by fishermen, are found swimming near the surface; no 
sufficient cause has been discovered for this condition, as they are no 
more afflicted with parasites than healthy fish. 

IMPORTANCE AND ABUNDANCE. 

The trout fisheries of the Great Lakes are second in importance 
commercially, the whitefish ranking first. At one time trout were so 
plentiful that they did not command a price at all proportionate to their 
edible qualities, but as the fishing continued the catches decreased, 
until about the year 1886 the market price of trout became equal to 
that of its more delicate rival. At this time it became evident to the 
Federal and State governments, as well as to those dependent upon 
this industry for a livelihood, that decisive steps ought to be taken 
toward providing against the extermination of this valuable food-fish. 
Artificial hatching was commenced that year with the object of restock- 
ing the Great Lakes. The work progressed only in a limited way up 
to 1892, when the output of both the United States and Michigan Fish 
Commissions reached something like its present proportions. During 
the season of 1895 the United States Fish Commission station at 
Northville secured over 11,000,000 lake-trout eggs. As indicative of 
the success attending the plants of lake trout, it may be remarked that 
for a short period during the season of 1896 the fishing-boats, which 
had been working to their fullest capacity, ceased operations, the 
market being glutted and the remuneration not being commensurate 
with the labor, hardship, and capital invested. 



Report U. S. F. C. 1897. (To face page 105 ) 



Plate 32. 




MANUAL OF FISH-CULTURE. 105 

The method of capture is by gill nets, pound nets, hook and line, 
aud in winter by spearing through the ice. The majority, however, 
are taken from gill nets operated by steam tugs. These boats are fitted 
out with the most approved appliances of their trade and have quar- 
ters on board for the men employed, usually a crew of 8 or 10. Some 
of the tugs carry 5 or 6 miles of nets and catch in one lift from 1,000 
pounds to 4 or 5 tons of trout. Fishing is done from the time the ice 
breaks up in the spring until late in the fall or early winter, the work 
ceasing only when the weather and ice no longer permit operations. 
In some localities the water becomes so warm during summer as to be 
detrimental to the nets, and consequently at such points there is a 
lull in the work for a few weeks. Lake trout spawn on the reefs and 
live in deep water during the remaining time, and their migratory 
habits govern the movements of the tugs, the fishermen necessarily 
moving from one point to another. The small gill-net boats, carrying 
sails and handling a few hundred feet of nets, confine their operations 
to more shallow water and fish only during the spawning season. At 
Detour, Lake Huron; at some points in Lake Superior, and on the 
north shore of Lake Michigan pound nets are in use, but usually these 
nets are not used to any great extent for the capture of lake trout. 

NATURAL SPAWNING. 

Spawning commences the last of September in Lake Superior and 
later in the lower lakes, since the water does not become sufficiently 
cool here as early as in the headwaters. In Lakes Huron and Michi- 
gan the height of the season is in the early part of November, and 
spawning continues to the first of December. The spawning-grounds 
are on the reefs of "honeycombed" rocks, 10 to 15 miles from shore, 
and during the reproductive period vast numbers of fish visit these 
places, spawning in a depth of from 1 to 20 fathoms. Owing to the great 
depth of water, the shyness of the fish, and the severity of the weather 
at this time, nothing definite has been determined as to the fish's 
maneuvers while spawning. The supposition is that the female lies 
over an indentation of the rocks and allows her eggs to settle into the 
"honeycomb" cavities; fragments of the rock with the cavities filled 
with eggs having been hauled in by fishermen when lifting their nets. 
No doubt the general characteristics of the Salmonidce are carried out 
by the lake trout as far as the conditions in which they exist permit. 

An instance has been known of a Mackinaw trout of 24 pounds weight 
containing 14,943 eggs; but not over 5,000 or 6,000 eggs are commonly 
found, and 1,000 eggs to the pound of fish may be accepted as a general 
rule, after the trout have attained maturity, at three years of age. 

A much smaller variety, called the shoal trout, is found in Lake 
Huron in the vicinity of Alpena, and in Lake Michigan near Charle- 
voix and Northport, but its weight compared with its length is greater 
than that of the true Mackinaw trout, and the markings and appearance 
of the two also differ. The shoal trout spawns in September, about a 



106 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 

month earlier than the lake trout, on a cobble, bowlder, or gravel 
bottom, and in from 2 to 8 feet of water. 

OBTAINING THE EGGS. 

During the spawning season men are employed by the different 
lake-trout hatcheries to accompany the tugs to their fishing-grounds 
and strip the ripe fish as they are taken from the nets. These " spawn- 
takers," or "strippers," must possess strong constitutions to withstand 
the many hardships to which they are subjected. Where very exten- 
sive nets are operated by a boat and fishing is exception ally good, two 
men are detailed to the same ground, one as spawn-taker, the other as 
helper. Pans, pails, and dippers are taken on board and made ready 
by the time the nets are reached. As the net is lifted the men disen- 
tangle the trout and throw them on deck, where the spawn-takers sort 
them over, taking the eggs from ripe females and impregnating them 
with milt from the males. During very severe weather the fish are 
thrown into the hold instead of on deck and the work is done there. 

The manner of taking the eggs is similar to that used in taking 
spawn from other trouts and salmon. First, the female is taken and 
the eggs, if mature, are gently stripped into an ordinary milk-pan and 
then impregnated with milt from the male. This operation is repeated 
until the pan is about half filled, when the eggs are "washed up" and 
poured into a 5-gallon pail. The "washing-up" process is performed 
by filling the pans with water and then allowing it to run off, repeating 
the same until the water which is poured off no longer appears milky; 
as the specific gravity of the eggs prevents their rising to the surface 
this can be done without loss if ordinary care is exercised. The pans 
are refilled and emptied in the same manner until the pail is half or 
three-fourths full, when it will contain about 75,000 eggs ; other pails 
or buckets are brought into use as often as necessary. To keep the 
eggs from dying, the water is changed in the large pails every hour 
until the eggs are taken from the boat and transferred to flannel trays or 
floating-boxes. All pans, pails, and other metallic apparatus are coated 
with asphaltum paint to prevent rusting, as rust is fatal to the eggs. 

When the weather is so cold that there is any chance of eggs 
freezing to the pan, two pans are sometimes used. The outside one is 
partly filled with water, upon which floats the pan that is to receive 
the eggs as they are stripped. The pan of water protects that part of 
the inside pan where the eggs rest and in that way their temperature 
is kept above the freezing-point. 

SHIPPING EGGS TO THE HATCHERY. 

When spawn-takers are operating at a distance the eggs are held at 
field stations located at convenient points, whence they are sent to the 
hatching-house as soon as possible, but if the stations are at isolated 
points on the lakes it is often necessary to hold the eggs for several 
days, and occasionally weeks, before means of transportation can be 
obtained. In such a case the eggs are held in floating-boxes, which 
are made 2£ feet by 1£ feet by 1 foot, with the ends rounded up about 6 



MANUAL OF FISH-CULTURE. 107 

inches; the sides and ends are 1-inch pine and the bottoms £ inch-mesh 
iron wire cloth, which is continued over the rounded ends. Cleats are 
nailed on the sides, one end somewhat lower than the other, to give the 
box a tilt when placed in water. Each box carries safely about 180,000 
eggs, and when it is filled is anchored either in running water or in a 
sheltered cove of the lake. In the former case a current of water is 
kept passing through the box, while in the latter the eggs are given a 
slight motion by the action of the waves upon the surface of the water. 




Floating-box. 

When eggs held in floating-boxes are to be shipped they are dipped 
into pails and taken to a place arranged for packing them, located 
at no great distance away, where a table upon which to place the 
trays may be improvised from any material at hand. 

The trays for packing the eggs are constructed by making a frame of 
f-inch square pine, 18 inches square, inside measurement, with white 
canton flannel tacked on one side. A case to contain the trays is made 
of ^-inch pine, large enough to hold 19 of these trays one over the other, 
allowing for a surrounding air-space of half an inch. Half-inch cleats 
are nailed on the bottom and at the corners of the box on the inside, so 
that the trays are securely held in position. A hinged door is at the top, 
handles are at the sides, and the whole is painted and of neat appearance. 

For transferring the eggs from pail to tray a graduated dipper is 
used, which has a capacity of about 10,000 eggs, the number usually 
placed upon each tray. Thus, in a case containing 18 trays 180,000 
eggs may be stored. A dipperful is placed upon each tray. The canton 
flannel holds water for some time, and if a little is poured upon the 
eggs, which are at first bunched in the center, they settle and spread, 
and by a slight dexterous movement, acquired by practice, are evenly 
divided over the tray. Ten thousand eggs on a surface 18 inches by 18 
inches are about two deep, and if kept at the proper temperature and 
handled carefully they may be carried a long distance. After the eggs 



108 EEPORT OF COMMISSIONER OF FISH AND FISHERIES. 

are spread upon the tray it must be drained before being placed in the 
case, for eggs slightly moistened will live for a longer time in open air 
of the right temperature than in dead water. The tray is easily 
drained by slightly tipping it, so that the water will run out at the 
edges where the flannel is tacked on the frame. The trays are then 
placed in the case, eighteen tilled, the top one empty. 

If the case is to pass through a varied air temperature, moss is 
packed in the space between the trays of eggs and the sides of the 
shipping-case for protection against abrupt changes in the weather. 

When necessary to hold eggs on the trays for any length of time, as 
is often the case, each tray must be taken out and sprinkled with water 
at least every 24 hours. When they are held for a longer period than 
4 or 5 days they must be taken from the trays and placed in a tub of 
water and there washed in the same manner as described in taking 
spawn. When adding water, care is taken that it does not strike t<he 
eggs with such force as to injure them, the dipper either being held down 
in the eggs or the water poured against the side of the tub a little above 
the surface of the spawn, which gives them a steady whirling motion 
and at the same time does them no injury. 

The manner of transferring eggs from trays to a tub is very simple. 
After filling the tub with water to about a third of its capacity, the 
tray is placed in water at an angle of about 45° with its surface. Most 
of the eggs will slide down this incline into the tub, and what few 
remain may be washed down by pouring a little water on the uppermost 
side of the tray. After the eggs have been given a good washing they 
are replaced on the trays and returned to the cases, as described above. 

The eggs are shipped in charge of a messenger, if possible, to see that 
the cases are not roughly handled or tilted and the contents jarred or 
bunched while being placed in the baggage car. While on the road 
they must be kept in the coolest place on the car, providing that the 
temperature is not below 28° or 30°. 

It can be readily seen that the percentage of lake-trout eggs hatched 
can not be so large as with other species of trout. The rolling and 
pitching of the tugs and other boats upon which the spawn-taker is 
operatin g prevents the eggs from separating naturally. The time during 
which this should take place would be, approximately, within the first 
30 minutes after they are taken, and as the boats are out from 5 to 24 
hours or longer, when shore is reached the time is long j>ast when 
quiet is of any value. Besides, the temperature often falls far below 
freezing, and all the precautions that can be taken will not prevent a 
considerable percentage of the eggs becoming chilled, although there 
may be no ill effects discovered until after they reach the hatchery. 
Other losses often occur through accident and the carelessness of those 
handling the cases while en route to the hatchery. Taking everything 
into consideration, it may be considered excellent work if an average 
of 70 per cent of eyed eggs and fry is turned out. In exceptional cases 
as high as 90 per cent have been hatched. 



MANUAL OF FISH-CULTURE. 109 

THE HATCHERY. 

The hatching-trough or tank in use at Northville combines the prin- 
ciples of both the Clark and the Williamson hatching apparatus and 
is therefore called the Clark- Williamson hatching-box. It possesses 
more advantages than any other in use for the development of a large 
number of -eggs; a thorough circulation is obtained for thousands, the 
apparatus is simple, and the eggs may be readily handled for picking, 
cleaning, etc. It consists of a trough of any length according to the 
number of fry to be held, 18f inches wide inside and 1 foot deep, with 
partitions to divide it into compartments, and is constructed as follows: 
Only the best lj-inch pine is used, all planks containing knots, heavy 
pitch, etc., being rejected, and the sides and ends are each made of but 
one piece of lumber. The bottom is made first, the strips of different 
widths plowed and tongued securely, and all joints laid in white lead. 

Eeferring to figs. 1 and 3, page 110, three-quarters of an inch down 
from the top of the sides is a f -inch groove (A) running the entire length 
ot the trough. The partitions, dividing the trough into compartments, 
18f inches by 9f iucnes by 12 inches, are mortised ^ inch in the sides ; 
the first and each alternate partition (B) is fixed J inch from the bottom 
of the trough to allow the water to pass under it; the second and each 
alternate partition (C) is mortised into the bottom, and at the top is cut 
out so as to leave a space 14f inches long by 1£ inches deep for the 
water to pass over. In the bottom of the boxes thus formed a £-inch 
strip (D) $• inch wide is nailed to the sides; upon these the bottom trays 
rest. A crossbar (E), with f-inch block (F) to hold the trays securely 
in place and prevent them from rising in the water, is made to fit in the 
grooves at the sides of the trough. 

The capacity of the troughs may be doubled by the addition of a 
second row of boxes, one side of the first tank acting as a partition 
between the two rows. Each box holds eleven trays (G). Ten of these 
are filled with eggs, the eleveuth, or top one, acting merely as a cover 
to prevent the eggs on the tenth tray from being carried off by the 
current. The trays are made of |-inch mesh galvanized wire cloth, 
tacked upon frames 16 inches long, 7 inches wide, and f inch thick. 
Both the trays and tanks are given three coats of asphaltum paint 
before being used, and one coat at the beginning of each succeeding 
season. Eleven of such trays, in the box described, will fill the com- 
partment to within f inch of the groove in the sides of the tank ; then 
the crossbar with the f-inch feet holds them securely in place. The 
tanks are set upon iron standards cemented in the floor, and are given 
a pitch of £ of an inch to the foot. The height of the tank from the 
floor is a matter of convenience to the operator, depending on the fall 
of water available. 

The water enters through a 1-inch pipe at the head of the tank, flow- 
ing down through the first division, up through the second, and so on 
to the lower end. Where water is scarce, two troughs may be made to 



110 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 



utilize the same supply by placing one after another, the upper end of 
the lower trough being from 8 to 12 inches lower than the overflow of 
the upper trough ; this gives a good aeration and will be found to answer 




Clark-Williamson Trough. 



nearly as well as though fresh water was conducted to the tank. 
Should the supply be taken from a creek, lake, or other reservoir ex- 
posed to changes of weather aDd drainage from the surrounding land, 



MANUAL OF FISH-CULTUEE. Ill 

or if it abounds with, aquatic insects, it is quite essential to have some 
kind of filtration, otherwise the eggs may be injured by animalculse 
or coated with sediment, the trays clogged with refuse, the circulation 
stopped, and in the end a majority of the eggs lost. Many filters 
have been devised, all of which are good, but a simple and effective 
contrivance is made by tacking medium-weight flannel to wooden tray 
frames and placing them at the head of the tank directly beneath the 
head of water, the number used at one point being governed by the 
amount of sediment or other foreign matter present. 

At North ville, as a convenience in caring for eggs, a shallow "picking- 
trough" is used, 40 feet long, 10 inches wide, and 2£ inches deep, with 
a £-inch strip, § of an inch wide, nailed aloug each side of the bottom, 
upon which the trays rest, to give a good circulation while the eggs are 
sorted over. The trough has a fall of not more than J inch throughout 
its entire length, and it is fed by a flow of about 2 gallons of water 
per minute. A dam at its lower end raises the water 1^ inches, not 
entirely covering the trays. This is a point that must not be over- 
looked, for if the water flows over the tops of the trays many of the 
eggs and fry will be apt to escape through the waste-pipe. 

CARE OF THE EGGS AND FRY. 

Upon their arrival at the hatchery the eggs are taken from the 
shipping-cases and turned into tubs, whence they are removed to the 
hatching-troughs. In removing eggs from the flannel shipping- trays 
to the tub the same method is followed as in washing eggs that have 
been held in cases for several days. The transfer should take jflace in 
a temperature not higher than 45° or 50° F., and if the eggs are held 
in the tubs for any length of time they are given a change of water 
every 30 minutes. 

Great care is necessary in transferring eggs to the hatching-trough 
in pails. To guard against any shock, the pail is partially filled with 
water, and the eggs are carefully taken in the dipper, which is lowered 
into the pail in such a way that the eggs will glide into the water and not 
fall upon it. The pail when filled is placed upon the trough as near as 
possible to the box for which the eggs are intended, and by means of a 
perforated dipper with a capacity of 20 ounces, or 4,000 eggs, they are 
transferred to the hatching-boxes. A tray is placed in the water and 
one drpperful poured upon it, whereupon a second tray, placed on top 
of the first, is served in like manner, and this is repeated until ten trays 
are filled. The eleventh, or cover tray, is left empty, and the whole 
apparatus is held in place with a crossbar or binder. In two double 
troughs, containing 64 boxes and occupying a floor space of 100 square 
feet, 2,560,000 eggs may be safely carried with 22 gallons per minute 
of good spring or lake water, well aerated. 

To estimate the number of eggs laid down, a fractional portion of a 
quart is counted several times until a satisfactory average is arrived at; 
this has given 200 to the fluid ounce, or 6,400 to the quart. 



112 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 

For the first few weeks after the eggs have reached the hatchery- 
close attention must be given to prevent the growth and spread of 
fungus throughout the tank. The eggs must be carefully hand-picked, 
and the trays and boxes kept thoroughly cleansed from slime and other 
impurities. If a heavy rain should wash dirt, refuse, etc., into the 
supply reservoir and thence to the hatchery, the eggs must be cleaned 
to prevent their smothering. No filter, practical for use in a hatchery, 
has been invented that will entirely remove injurious substances. 

To remove the egg-trays from the boxes for sorting, the binder is 
first slipped out from the grooves and the trays taken out separately, 
each rising to the surface as the one above it is removed. All the 
trays are taken out of one box and placed one after another along 
the picking-trough. The dead eggs and "ringers" — the latter not 
appearing until in the later stages of incubation — are then picked out 
with small metal tweezers. The eggs will turn white when dead, and 
if allowed to remain upon the trays a fungus will soon appear upon 
their surface and spread its growth until all the eggs within a short 
radius are affected ; these in their turn will be smothered and become 
fungussed in the same manner. 

When it is necessary to change the position of the eggs in order to 
bring those at the bottom to the surface a soft feather is used, and if 
manipulated carefully it will have no injurious effect. After the eggs 
have been carefully sorted the trays are again placed in the hatching- 
box. The eggs are looked over at least every three days during the 
first five or six weeks; at the end of that time, in a water temperature 
of from 40° to 45° F., the eye-spots will show up plainly, and from this 
stage to the breaking of the shell less labor need be expended in this 
direction, for the eggs are not so susceptible to fungus, etc., as in the 
early stages. At this period unimpregnated and imperfectly developed 
eggs are easily distinguished and taken out at one picking, leaving 
practically only those that will ultimately hatch as perfect fry. 

For washing the eggs when coated with sediment a large galvanized- 
iron pan, about 2£ feet long, If feet wide, and 4 inches deep, is used; 
this is nearly filled with water and a tray floated on its surface. The 
eggs are gently moved about with a feather, and by submerging and 
quickly raising the tray the eggs will be left as clean as when first 
taken. It is necessary to be very careful to give no sudden jar or 
shock to the eggs, for up to the time the eye-spots begin to appear they 
are very delicate and must be handled accordingly. It is better to 
allow a small amount of dirt to remain on the eggs than to under- 
take washing them, which should only be done when the coating of 
sediment becomes dangerously heavy. The boxes may be washed when 
the trays are in the picking-trough, but to wash the trays is difficult, 
yet very necessary in case they become covered with slime. 

The eggs may be transferred to a clean tray without serious harm 
by placing the dean tray face downward upon the dirty one, and by a 
quick movement reversing their positions, submerging both trays in a 



MANUAL OF FISH-CULTUKE. 113 

pail of water. This will deaden the fall of the eggs from one tray to 
the other and free what few adhere to the first tray. 

In a water temperature of from 40° to 45° F., hatching will begin in 
from 75 to 90 days. The dark hue of the egg as a whole, the distinct 
outline of the fish, and its convulsive movements show the approach 
of the hatching period. If the weather is clear and cold these indica- 
tions may continue for some time, but with the advent of a single warm 
day more than 50 per cent of the fry are apt to break their shells. 

As the total number of eggs received at the hatchery has decreased, 
in order to determine the number of fry that will be hatched they are 
now measured again by first emptying the eggs in the large pan 
described above, and then placing 4,000 each upon trays, in this case 
made of wire cloth with a -^-inch mesh. Should the temperature 
remain uniform the hatching will cover a number of days, but a sudden 
rise or fall in the tem'perature will have a marked effect in either 
advancing or retarding the further development of the eggs. 

The dead shells from the hatching fish must be removed or they 
will clog the trays and stop the circulation of water. To provide 
against this, one box of trays is emptied into a pan of water and the 
eggs stirred with a feather; the shells rise to the top and can be easily 
poured off, and by repeating this operation several times the hatching 
fish are entirely freed from this refuse. In returning the fish and eggs 
to the trays they should be divided as equally as possible among the 
ten trays. The necessity for this depends on the rapidity of hatching 
and perhaps a single box need be served in this manner only three 
or four times during the hatching period. 

The care of the fry from this time to their distribution, if distributed 
before the absorption of the food-sac, is somewhat similar to the treat- 
ment described for eggs. Monstrosities, " blue-sacs," and dead fry are 
picked out as soon as they are discovered. The yolk-sac attached to 
the fry will be gradually absorbed and the fry so increase in size that 
4,000 overcrowd one tray, and when the sac is about half gone, which 
is in about three or four weeks after the fish are hatched, it is necessary 
to reduce the number upon each tray to 2,000. 

DISTRIBUTION OF THE FRY. 

Lake trout should either be planted while the food-sac is still visible, 
or not until they possess the vitality of the yearling. Trout planted 
when the food- sac is within one or two weeks of complete absorption 
have sufficient nourishment to sustain life until they are acclimated to 
their surroundings, as well as the natural impulse from the beginning to 
take the minute particles of food Avhich they find. As from 2,000,000 to 
4,000,000 lake trout are hatched at Northville annually, it is impossible, 
with the present facilities, to hold them all in rearing-troughs and ponds 
until they become yearlings, and the fry are usually distributed direct 
from the hatching-boxes. 

F. C. K. 1897 8 



114 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 

In shipping them to their destination, 10-gallon round- shouldered cans 
are filled to within a foot of the top with the water used in hatching. 
One trayful, or 2,000 fry, is put in each can, and as soon as it is filled, 
enough ice is added to bring the temperature down to 38° or 40° F. If 
the fry are to be planted in the Great Lakes, the cans are transferred 
from the car, upon its arrival at its destination, to a fishing-tug and 
conveyed to the reefs or natural spawning-grounds of the lake trout; 
here the cans are lowered into the water and the fry allowed to escape 
and in a few moments they disappear from the surface and sink to the 
bottom. 

PACKING EYED EGGS FOR SHIPMENT. 

When the eye- spots are plainly visible, the eggs can be packed and 
successfully shipped to any part of the world, if kept at a uniform 
temperature. The trays used for this purpose are made like those used 
in shipping green eggs from the field station to the hatchery. For 
100,000 eggs 16 trays, 18 inches by 18 inches, are required; for 50,000, 
8 trays, 16 by 16; and for 5,000 eggs, 5 trays, 8 by 8. After they are 
packed, the trays are placed one upon the other and crated together by 
nailing a cleat on each side from the foundation to the top board. The 
packing-case is made large enough to admit of an air-space of 1 inches 
around the top, bottom, and four sides of the crate, when it is placed 
in position. Eope handles are inserted at the sides. 

The temperature of the packing-room should not be higher than 40° 
nor lower than 26°. A temperature of from 28° to 30° is preferable. 
The canton- flannel trays are first soaked in water, drained, and then 
placed upon a table to receive the eggs. Wooden frames of finch 
square strips, made so as to fit inside the frames of the packing- trays, 
are then inserted. A box of eggs, previously picked and cleaned, is 
taken out, drained, and carried to the packing-room. The eggs are 
carefully brushed from the wire trays upon the flannel trays with a 
feather and spread evenly over the surface. To divide the eggs among 
the flannel trays is not difficult, as there are 40,000 in the hatching- 
box, or 4,000 to the tray. The inner wooden frame is now removed, 
leaving a finch margin on all sides between the eggs and the tray 
frame, and a piece of damp mosquito netting is laid over the eggs, 
extending 1£ inches beyond the sides of the frame. This netting is 
pressed down at the inside corners of the tray and all along next to 
the frame, in order to hold the eggs in position and avoid their coming 
in contact with the wooden frames. Over this netting is scattered 
sphagnum moss, \ to f of an inch deep. This moss is gathered in the 
fall, and is prepared by being soaked in water and wrung out with a 
clothes- wringer. It must be free from all sticks and decayed matter 
and thoroughly wrung out, picked apart, and made fluffy, for if used 
upon the eggs in a compact mass, the supply of oxygen would not be 
sufficient for their maintenance while en route. It should be moist, but 
not so wet as to drip on the eggs. 



MANUAL OF FISH-CULTURE. 115 

When packed the egg-trays are placed upon a foundation-board, made 
the same size as the trays and covered with moss. At the top another 
board of the same dimensions is laid. Cleats are nailed on all four 
sides and fastened to the top and foundation boards, making a firm 
crate, which can be handled without danger to its contents. 

If the temperature of the packing-room is not below freezing, the 
trays are placed out of doors before they are crated, to allow the moss 
upon the eggs to become slightly frosted. Eggs at this period may be 
subjected to a very low temperature without injury — in fact, may be 
enveloped in a thin coating of ice, and if shipments are made when 
the weather is too warm for frosting the results are not so good. 

A packing-case, provided with rope handles, is prepared large enough 
to admit of an air-space of 4 inches around the top, bottom, and four 
sides of the trays. The bottom is filled 4 inches deep with fine shavings, 
the crate of eggs is placed upon them, and more shavings packed all 
around between the trays and the case. The packing is carefully done, 
a few shavings being thrown in and pounded down before more are 
added, in order that the trays may be held securely in the center of 
the case. Shavings are filled in on top, the cover screwed on, and the 
box is ready for shipment. 

In transit the eggs must be kept in a cool place, though not allowed 
to freeze ; and if this precaution is taken, and they are not unneces- 
sarily jolted, they will be found in good condition when unpacked. 
Hundreds of thousands of eggs have been thus shipped from North 
ville during the past few years, the eggs arriving in fine condition and 
with practically no loss. 

For foreign shipments a double box is used. The inside one is made 
2£ inches larger on all sides than the crate of trays, and the outside 
one large enough to make a 5-inch space on all sides when the smaller 
box is placed within it. The trays of eggs are prepared as in ordinary 
shipments, and. when crated, are placed in the smaller box upon a 
frame which is constructed from a £-inch strip, 2£ inches wide, tacked 
at right angles to the inside and bottom of this box. In the space 
thus formed between the crate and the box is packed finely chopped 
ice, water from the melting ice being drained off through a half dozen 
small openings in the bottom of the box. This box is now packed 
according to the same plan as that followed with shipments for a short 
distance. Where there is an opportunity it is advisable to have the 
case unpacked while en route and fresh ice added. Eggs have been 
shipped in this manner to England, Mexico, New Zealand, Japan, and 
South America, and have reached their destinations with little loss. 

FEEDING AND REARING LAKE TROUT. 

Lake trout fry held for rearing are kept in troughs until they are large 
enough to be transferred to ponds. These troughs at Northville are 
12 feet long and 2 feet 7 inches wide, with a 1-inch partition running 
through the middle its entire length, thus forming two troughs, each 



116 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 

1 foot 2 inches wide. At intervals of 18 inches, cleats If inches high 
are mortised across the bottom, and in the sides of the trough, at 
the ends of the cleats, grooves are made to admit the placing of a fine- 
meshed vertical screen, which can fit tightly to the partition at the 
bottom. Everything is coated with asphaltum paint. The trough has a 
fall of one-fifth of an inch to the foot, the overflow being at the end 
through a tin spout. Another trough may be set at the lower end of 
the first, provided, as with hatching-troughs, a sufficient fall is given for 
aeration. 

A week or ten days before the disappearance of the yolk-sac, which 
will be absorbed in five or six weeks, with water at a temperature of 40° 
to 45°, the fry intended for rearing should be transferred to the troughs. 
In a single trough of the size described, 15 gallons of spring water per 
minute, with a temperature ranging from 45° to 50° F., will support 
8,000 fry during the first few weeks they are held. Up to this time it is 
not necessary to insert the vertical screens except at the head and out- 
let, but as the fry increase in size they become restless, snapping at each 
other and crowding together in a mass at the head of the trough, and 
then it is necessary to thin them out and separate them by subdividing 
the troughs, holding an equal number of the fry in each of the compart- 
ments. The action of the fish determines when this should be done. 
The use of warm water hastens the development of the fry, the same as 
it does with the eggs. 

For the first four weeks the fry are fed four times per day on finely 
chopped beef liver, ladled through a close screen to remove all lumps. 
The liver is diluted with water and the mixture fed to the fry with a 
feather. For some days they do not appear to take their food, but the 
routine is continued, and as soon as the sac is entirely consumed they 
commence feeding. No rule can be laid down prescribing a definite 
amount of food, but the fry are fed till their appetites are appeased and 
every fish has obtained a morsel. Some days they display more hunger 
than usual, a warm day especially increasing their appetites. After 
they begin to feed well the liver may be given to them but three times a 
day, more being thrown in at a time. 

The troughs must be cleaned out daily by turning on an additional 
supply of water— -not so much that the fish will be carried against the 
screen — and the foul matter stirred up from the bottom with a feather 
and worked through the wires with a small sponge. Twice a week the 
sides and bottom are sponged off. 

Three months after being transferred to the feeding- troughs, trout 
will take food well and be from 1 to 2 inches long. They are then ready 
to go outside to the rearing-ponds. These ponds are about 32 feet long 
by 5 feet wide, with from 10 to 20 inches of water, and have a minimum 
water supply of 20 gallons per minute. The bottom is graveled and 
the sides constructed of planks or cobblestones, and on the sides where 
the sun strikes the warmest during the day a board shades the trout 



MANUAL OF FISH-CULTUEE. 117 

from tlie direct rays. A pond of this description will accommodate 
10,000 lake trout three or four months old. As they increase in size 
this number may be diminished, a great deal depending upon the 
quality and temperature of the water. 

The temperature of the water should never be higher than 65°; 
preferably from 48° to 58°. 

As when kept in rearing-troughs, the fish are now fed the amount 
they seem to desire, being neither overfed nor starved. The liver, not 
so finely chopped as before, is thrown in with a spoon. At the first 
feeding the fish may be somewhat wild and scatter over the pond, but 
after one or two days they will collect at one point and take the food 
greedily. After four weeks' time they are fed only twice per day, and as 
they increase in size, coarser liver is given to them. Food is thrown 
in slowly, and no more given at one time than the fish can eat, for 
waste matter soon becomes foul, and unless drawn off will speedily 
cause sickness. 

In from 10 to 12 months after hatching, lake trout artificially reared 
measure from 4 to 8 inches in length and are ready for planting. This 
is done in the same manner as with fry, 100 fish being placed in each 
can for transportation. 

DISEASES. 

The diseases to which lake trout are susceptible are those common to 
all other trout. They are caused by impure water, poor food, injuries 
received, and the attempted cannibalism of their neighbors. The first 
three of these causes can be guarded against, but the last is much more 
difficult to prevent. At the first sign of cannibalism the fish must be 
thinned out, and, if feeding well, transferred to the rearing-pond, where 
they will have greater range for development. In fact, for any of the 
diseases this will prove of more benefit than anything else. 

It is beneficial to treat the fry with salt twice a week by shutting 
off the water and sprinkling salt in the trough until a weak brine is 
formed. The fish must be watched closely, and as soon as they show 
any signs of "turning up" a full head of water must be turned on 
until all the brine is washed off, after which the supply may be reduced 
to the regular amount. A small quantity of swamp earth should be 
scattered in the tanks about once in two weeks, merely enough to dis- 
color the water for a few moments, and allowed to wash off gradually 
with the current of the water. 



Report U. S. F. C. 1 897. (To face page 119) 



Plate 33. 




THE WHITEFISH. 



DESCRIPTION, COMMON NAMES, ETC. 

The common whiteflsh (Coregonus clupeiformis) is eminently a lake 
fish. It exists throughout the Great Lakes region, and is especially 
abundant in lakes Brie, Huron, Michigan, and Superior. The eastern 
limit of its range is Lake Champlain, and it is found in Lake Winnipeg, 
and possibly farther west. It is landlocked in Otsego Lake, New York. 
Efforts to introduce it into new waters in the States of the Pacific Coast 
and Eocky Mountain region have not as yet been successful. 

Its body is rather long and compressed, and the back, especially in 
adults, is arched in front ; the greatest depth is about one-fourth the 
body length. The head is small and short, contained about 5 times in 
the length of the body; the snout is blunt; the mouth is small and 
nearly horizontal with the lower jaw included; the maxillary is short 
and broad, reaching to a point under the pupil; the mandible extends 
to a point under the posterior edge of eye. The eye is small, its diam- 
ter being about one-fifth the length of the head. The rays in both the 
dorsal and anal fins number 11. The number of rows of scales along 
the side of the body varies from about 82 to 92, with about 11 above 
the lateral line and 8 below. The gillrakers number about 28, of which 
10 are on t\e upper arm of the gill-arch; the longest are contained 
about twice in the length of eye. The general color of this fish is a 
satiny white, with a faint olive-green shade on the back. The fins are 
uniformly white, except the caudal, which normally has a dark edge. 

This fish has a number of common names in different parts of its range. 
It is the whiteflsh par excellence of the United States and Canada. As 
found in Otsego Lake, New York, it is inappropriately called "Otsego 
bass." In allusion to its humped back it is called "high back white- 
flsh," "bowback whiteflsh," "buffalo-back whiteflsh," and other similar 
names, in Lake Superior. 

While more is known of the habits of this species than of any other 
member of the group, many phases in its life are still obscure, as it 
remains in deep water most of the time. Besides the regular annual 
movements of the schools to the spawning-grounds, there are other 
well-marked migrations in some lakes. Whether these depend on food, 
temperature, enemies, or other causes, is not known. Owing to its 
small, weak mouth, it is seldom taken with a baited hook. It subsists 
on minute animal food, chiefly crustaceans, mollusks, and insect larvse. 
The food of the fry and young fish is almost wholly small crustaceans. 

119 



120 REPORT OP COMMISSIONER OF FISH AND FISHERIES. 
COMMERCIAL AND FOOD VALUE, ETC. 

The whitefishes are by far the most important group of fresh-water 
fishes of North America, probably of the world. The common white- 
fish is the best of the tribe, but some of the others nearly equal it in 
merit, and all are more or less esteemed as food. Among the fishes of 
the Great Lakes the common whitefish ranks next in value to the lake 
herring, lake trout, and wall-eyed pike. In 1893 the catch in the United 
States was over 8,000,000 pounds, having a value of over $330,000. If 
to this is added the yield of other species (namely, about 3G,000,000 
pounds of lake herring, valued at $536,000, and upward of 3,000,000 
pounds of other whitefish, valued at $85,000), the aggregate is over 
47,000,000 pounds, having a value of $951,000. The market value of 
the whitefishes taken in 1893 in the British Provinces was reported as 
$1,535,000, a sum representing about 30,000,000 pounds. 

The common whitefish reaches a larger size than any other species 
of whitefish in the United States. Examples weighing over 20 pounds 
have been taken, but the average weight is under 4 pounds. 

Whitefish fishing is done chiefly with gill nets set at or near the bot- 
tom in comparatively deep water, although considerable quantities of 
whitefish are also taken in pound nets, trap nets, and seines. 

SPAWNING. 

The spawning season of the whitefish begins the latter part of Octo- 
ber and continues into December. At that season there is a general 
movement of the fish to shoal parts of the lakes, similar to the migra- 
tion of anadromous fishes from the ocean to the rivers; some of the 
the foreign whitefishes are typical anadromous species. After spawning, 
the fish return at once to the deeper water. 

The spawning habits of whitefish confined in pens have been observed. 
The fish rise to the surface, occasionally in pairs, sometimes, but rarely, 
in trios of one female and two males, the female emitting a quantity of 
spawn at each rise. The males, always the smaller fish, persistently 
follow the female and discharge milt at the same time the eggs are 
emitted. 

Whitefish reach maturity in the third or fourth year. A full-grown 
specimen deposits from 10,000 to 75,000 eggs, depending on the fish's 
size. A rule for determining the approximate spawning capacity is to 
allow about 10,000 eggs for each pound of the fish's weight. The eggs 
when fully swollen are an eighth of an inch in diameter, and 36,000 
make a fluid quart. They swell somewhat after impregnation. 

DESTRUCTION OP WHITEPISH SPAWN IN NATURE. 

In nature the eggs of the whitefish are subjected to the attacks of 
many enemies for nearly five months. The mud-puppy (Necturtis mac- 
ulatus), commonly known as "lizard" or "water-dog" by the people 
along the lakes, is especially destructive. During the month of Janu- 



MANUAL OF FISH-CULTURE. 121 

ary, 1897, many of these animals were pumped up with the water 
supply of Put-iu Bay station. The stomachs of a considerable number 
of them contained whiteflsh and cisco eggs, the contents of one stomach 
being 288 whiteflsh and 4 cisco eggs. 

Another voracious destroyer of the whiteflsh is the common yellow 
perch (Perca flavescens). The deck of a boat has been seen covered 
with the eggs of the whiteflsh and cisco pressed out of the stomachs of 
perch taken from gill nets the last of November on the reefs, where they 
had gone to feed on the eggs. 

The various smaller Gyprinidce and some other fishes, crawfish, and 
wild fowl make the eggs of fishes a considerable portion of their diet, 
those which require the longest period, in hatching, of course, suffering 
most. 

ARTIFICIAL PROPAGATION. 

The artificial propagation of whiteflsh has long since passed the 
experimental stage and has attained a high degree of perfection. The 
work can be carried on with great facility, and its value is especially 
apparent when it is considered that under natural conditions only 
a very small percentage of the eggs hatch, while through artificial 
propagation from 75 to 95 per cent are productive. Practically all the 
eggs taken for hatching purposes are obtained from fish caught by the 
commercial fishermen, which would otherwise be lost. 

The methods of culture hereafter referred to are those adopted at 
the Put-in Bay (Ohio) station, but these do not differ in auy essential 
particular from those in general use. 

In the fiscal year 1895-96 the United States Pish Commission hatched 
and planted 189,690,000 whiteflsh fry, and in the subsequent year 
95,049,000 fry were hatched and liberated in suitable waters. 

HOW THE EGGS ARE TAKEN AND TREATED. 

The taking, impregnating, and handling of the whiteflsh eggs are 
simple processes, but require great care at every stage. Eggs are 
often injured by undue haste in stripping, and many are lost by allowing 
them to fall too great a distance into the spawning-pan. Eggs are very 
delicate when first taken and before the absorption of water has made 
tlie investing membrane tense, and if roughly treated will be seen to be 
ruptured as viewed under the microscope. With care about four-fifths 
of the eggs will hatch. Improper attention to the impregnating process 
may also result in serious loss of eggs. While scarcity of milt may 
lead to the nonfertilization of the eggs, the manner in which the milt is 
brought in contact with eggs is a more common cause of failure. 

The eggs supplied by each spawn-taker should be examined daily, 
and if it is found that a considerable number have ruptured yolks it may 
be taken for granted that the spawn-taker has handled the fish and eggs 
roughly, and if many are unimpregnated it is evident that he did not 
use sufficient milt or that it was not properly applied to the eggs. 



122 KEPORT OP COMMISSIONER OF FISH AND FISHERIES. 

At Put-in Bay eggs are obtained from fish captured in pound nets 
and gill nets, often at considerable distances from the station. The 
spawn-taker, who is employed to take the eggs from the fish as they are 
lifted from the nets into the boat, has with him two or three 6-quart 
pans, coated with asphaltum varnish to prevent rusting, in which he 
takes the spawn ; a wooden keg or tin can holding from 10 to 15 gallons ; 
a 10-quart wooden pail, and a tin dipper. He is clothed in waterproof 
garments, and his left hand is covered with a woolen mitten for con- 
venience in handling the fish. 

After several ripe females and some ripe males are collected, a female 
is taken, and the body slime, which will interfere with impregnation if 
it falls into the pan, is carefully removed. The spawn-taker then 
grasps the fish firmly in his left hand, just forward of the tail, with the 
back of the hand downward, the fingers outward, the thumb above and 
pointing outward, the head of the fish being toward the spawn-taker's 
body. The right hand is placed under the fish just back of the pectoral 
fins, with the wrist pressing the head of the fish firmly against the body, 
the thumb outward, fingers inward, thus grasping the upper abdomen 
firmly. The fish is now at an angle of nearly 45°, the body forming a 
modified crescent, with the vent within 4 or 5 inches of the bottom of the 
pan. This position of the fish's body brings pressure on the abdomen, 
facilitates the flow of the eggs through gravity and the opening of the 
vent, and prevents injury to them from falling too far. (See plate 34.) 

Gentle pressure being now applied, the eggs flow in a steady, liquid 
stream about a quarter of an inch in diameter, and a considerable 
portion of them will be procured before the hand need be moved. As 
soon as the stream slackens the hand is slowly moved toward the vent, 
but only fast enough to keep the eggs coming in a continual stream. 
When it finally stops the hand is replaced in its former position and 
the process repeated until all the good eggs are procured. If, as is 
frequently the case, when nearly all the ripe eggs are emitted a consid- 
erable number of white ones appear, the work s'hould stop. 

The dry process of impregnation is now universally considered to be 
the better, and the pan in "which the eggs are taken is only dampened 
by dipping it into water before the stripping begins. After two or three 
females have been manipulated the milt from one or two males is added 
to the mass of eggs. This is done by grasping the fish between the 
thumb and fingers 2 or 3 inches forward of the vent and moving them 
toward the opening. The milt comes in a stream, an average fish pro- 
ducing about a teaspoonful. If ripe males are scarce the fish is laid 
aside, as he may be used again in a few minutes and considerable addi- 
tional milt procured. 

When the pan is one-half or two-thirds full of spawn and milt, the 
spawn-taker gently stirs the eggs to incorporate them thoroughly with 
the milt, using for this purpose the tail of a fish, from which the 
slime has been carefully removed. The pan is then partly filled with 
water and the mass again very gently stirred. After standing two or 



.Report U. S. F. C. 1897. (To face page 122.) 



Plate 34. 








, •■ ..-■■■ 


T& 


*fet 


ym~ 



STRIPPING A WHITEFISH. 



MANUAL OF FISH-CULTURE. 123 

three minutes, the water is poured off and fresh water added, and this 
is repeated until the water comes away clear, when the eggs are poured 
into the keg or can previously filled with water, and the work of taking 
spawn is continued. Before adding another lot those previously put into 
the keg are gently stirred. It is necessary to change the water on the 
eggs at least once an hour, and oftener if the weather is warm, and the 
eggs should he gently stirred to the bottom of the keg every 30 minutes 
until they are placed in running water in the hatchery. 

When the spawn-taker has finished he turns over the eggs to a man 
in charge of the field work, who cares for them until the collecting 
steamer comes, when they are taken aboard and transported to the sta- 
tion, some 2 to 5 hours having elapsed since they were taken. At the 
station the eggs are kept in the kegs in which they were placed by the 
spawn-taker and a stream of water of about 2 gallons per minute to 
each keg is kept running on them until the next morning, and they are 
stirred to the very bottom once an hour in the meantime. In this way 
the eggs are given time to harden with less injury than if they were 
immediately placed in the jars. 

Formerly in shipping eggs long distances they were kept in running 
water in kegs, under the care of a watchman, but it has been found 
much better to ship them in cases on trays. After having been in water 
8 or 10 hours, whitefish ova may be safely placed two or three layers 
deep on trays and shipped indefinite distances. If the weather is warm 
(55° or 60° F.) the cases must be surrounded with ice, or sawdust and ice. 

In placing the eggs on the trays a perforated -dipper is used and a 
little practice soon shows about how many to dip out for each tray, and 
if just enough water is left with the eggs a slight tilting of the tray 
will distribute them evenly over its surface. Then by setting the tray 
with one corner on the floor and the diagonally opposite corner raised 
3 or 4 iuches, the surplus water will soon dram off. This may be facili- 
tated by slipping a thin wooden wedge between the cloth and wood at 
the lower corner of the tray. 

In shipping a distance of 40 or 50 miles, the trays may be placed in 
the cases with no other protection from change of temperature than 
the wood of which they are constructed — an inch thickness of tray and 
an inch of case with an inch of air-space between — which is found to 
be safe in a cool car or room in a boat, but for longer distances about 
20 trays are fastened together with thin strips of wood tacked to either 
side and placed in a large case with from 4 to 6 inches of pine sawdust 
well packed on every side. 

After the eggs are placed on trays and drained, they are covered 
with a thickness of mosquito netting, well washed and left damp, and 
over this is packed enough damp moss to fill the tray even with the 
surface. If eggs are to go by express, unaccompanied by a messenger, 
directions are fastened to the case stating that they must be kept cool 
but not permitted to freeze. Whitefish eggs have been safely shipped 
in this way from Nortbville, Michigan, to Australia. If the eggs are 



124 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 

to be shipped a short distance — 25 to 50 miles — it is not necessary to 
cover them with moss. 

The trays used at the station are 16 inches square, outside, and are 
made of white pine f by 1 inch, mortised together at the corners with 
the widest side of the strip horizontal. On the bottom of these frames 
heavy canton flannel is tacked, so that the nap will come next to the 
eggs when in use. The cloth should be stretched very taut, otherwise 
it will sag on being wet and dried. The tacks are put 2£ to 3 inches 
apart, so that in a year or so it can be retacked between the ones first 
driven to take up the slack. The trays are made square, as they then 
go into the cases either way and time is saved in packing; square 
cases are also more convenient in storing and in handling generally. 
Such a tray will hold 50,000 eggs. 

If the eggs have to be retained for several clays in the field, they are 
sometimes kept in floating-boxes adapted for this purpose. (See descrip- 
tion of this box on p. 107.) But unless the conditions are very favor- 
able it is far better to place the eggs on trays, sprinkling them lightly 
once in two or three days. 

When taken from the kegs and trays at the hatchery the eggs are 
passed through a screen (with meshes sufficiently large to permit the 
passage of a single egg) in order to remove scales and other foreign 
substances that may be present. The screen is floated in a washtub 
partly filled with water, the wire netting being well submerged. 

For handling eggs and fry wooden kegs are by some preferred to 
tin cans, as they do not subject the eggs and fry to sudden changes 
of temperature, their contents are easily examined, and the water is 
more readily poured off without danger of losing eggs. The kegs are 
much lighter, only cost a third as much as cans, and last longer. For 
shipping in wagons or by rail, however, tin cans with covers are indis- 
pensable. Kegs should be made of white pine, painted outside but 
not within, and hold about 15 gallons each, and should be provided with 
iron drop handles. 

PENNING WILD FISH. 

The uncertainty of the seasons and the liability of failure to obtain 
spawning fish owing to severe storms which occur in November, make 
it desirable, wherever practicable, to capture fish in favorable weather 
and place them in pens until ripe. After the fish are driven off their 
spawning-grounds by severe storms, they do not return in large numbers 
during the spawning season, and the only way to insure a satisfactory 
supply of eggs is by penning the fish. 

Nets have been tried for penning, but they do not afford sufficient 
facilities for sorting the fish of various degrees of ripeness and the fish 
have to be handled too much, thus encouraging fungus growths on them 
and causing many to abort their eggs. Penning is best done in crates 
made of boards with openings sufficiently large to admit the free inter- 
change of water. The pens are generally made about 16 feet long, 3 or . 



MANUAL OF FISH-CULTURE. 125 

4 feet wide, and 4 to 8 or more feet deep. They should be placed end 
to end in two rows, some 3 or 4 feet apart with a plank walk between, 
for convenience in caring- for them. The fish must be handled as little 
and as gently as possible, otherwise the eggs will form into a hard mass 
and never ripen. One cause of injury is the scoop net with which they 
must be handled; the knots and the twine are so hard that they injure 
the delicate scales of the whiteflsh, which struggles violently when 
taken from the water. A net made by punching suitable-sized holes 
in a sheet of thin, soft, flexible rubber would be yielding and perhaps 
cause the least injury. 

HATCHING METHODS AND EQUIPMENT. 

At Put-in Bay the water for hatching is obtained from Lake Erie 
through a pipe that extends 75 to 100 feet into the lake. Pumps 
elevate the water to the loft of the hatchery, where it is received into 
supply-tanks, whence it is distributed by the usual methods of piping. 
The circular supply-tanks, two in number, are about 11 feet in mean 
diameter, 8 feet high, and have a capacity«of 5,000 gallons each. These 
tanks are necessary to give an equal pressure in the pipes and to 
provide a supply of water in the event of cessation of pumping. A 
gauge iu the boiler room shows the height of water in the tanks. 

Whiteflsh eggs are hatched in the McDonald jar and the Chase jar; 
the former is in more general use in the United States Fish Commission, 
although both give satisfactory results. The eggs are put into the 
hatching-jars by means of a dipper having a perforated bottom. The 
proper number to a jar is 3f quarts, as determined by a gauge; these will 
swell to 4^ quarts, which is about the proper quantity for the jars used. 

The form of the embryo whiteflsh can be seen in the egg by the use 
of a magnifying glass in from 10 to 15 clays and the eye-specks and 
color stars in from 15 to 20 days, the time depending much on the tem- 
perature of the water. The fry being hatched, the food-sac is absorbed 
in from 5 to 15 days, varying somewhat with the period of incubation. 
If hatching is long retarded by low temperatures, the sac will be nearly 
all absorbed when the fry hatches. 

The microscope is a great aid in whiteflsh culture, enabling the 
operator to determine the exact percentage of dead eggs and to a great 
extent the cause of their loss, thus allowing him to remedy some if not 
all the evils. For examining eggs in their early stages the microscope 
is placed horizontally, the eggs being held in a cell filled with water. 
This may be easily made by fastening two ordinary glass slides to a 
strip of wood an eighth of an inch thick, with a portion cut away to 
form a receptacle for the eggs. The wood is thoroughly saturated with 
asphaltum varnish, and after drying the sides should receive a thin 
coat, the slides being laid on and placed under pressure to dry. When 
dry an additional coat to the outer joints of contact will guard against 
possible leaks. 



126 REPORT OP COMMISSIONER OF FISH AND FISHERIES. 

If the egg be examined 6 or 8 hours after it is fertilized, the germinal 
disk will be found to have contracted to a saucer-shaped cap extending 
over about a fifth of the surface of the yolk. It is smooth and even, 
gradually thinning to a sharp outer rim, with a thickness in the center 
of the cap of about a fifth of its diameter. At this stage — segmentation 
not having commenced — the impregnated eggs can not be told from the 
unimpregnated ones. At 18 hours segmentation will be well advanced 
and the disk will have contracted into six or eight rounded nodules of 
uneven size, with well defined valleys between, there being no longer 
a sharp rim to the disk. At 24 hours — the best time to determiue 
the percentage of live eggs — the disk presents a somewhat similar 
appearance, except that it will be divided into 25 or more segments, 
easily seen uuder the glass; the disk of the unimpregnated egg of 
the same age forms an almost exact hemisphere, is perfectly smooth 
in appearance, and is therefore easily distinguished from the live egg. 
Segmentation now goes on rapidly, and at 72 hours the cells look under 
a 1-inch objective — a suitable power to use in this work — about the 
size of a mustard seed, the disk having in the meantime assumed an 
hemispherical shape. 

During the entire period of incubation, but more especially during 
the early stages of growth, the eggs should be worked as gently as 
possible; that is, only sufficient water should be used to keep them in 
slow motion and to prevent "banking." At the commencement they 
require about 6 quarts of water per minute to the jar, but later they will 
run with a quart less per minute. The eggs require constant watching 
for the first week or more, and although not considered an adhesive egg, 
agglutination takes place occasionally when the water becomes roily. 
Unless the "banks" so formed are separated by gently stirring them 
with a long feather (the long wing feathers of a turkey are suitable), 
the eggs forming the pack soon die and form a mass in the jar. 

In a few days, varying with the temperature of the water, the unim- 
pregnated and other dead eggs begin to "fungus" — that is, a growth 
makes its appearance on them and they rise to the top of the egg mass — 
when they must be removed by the use of a siphon, and if live eggs are 
among those drawn off, they must be set up in what are called " hospital 
jars," where the live and dead ones are more readily separated. 

The dead eggs are drawn off every day, otherwise they are liable to 
become loaded with silt from the water and sink, mixing with the live 
eggs and making it difficult to separate them. 

For the removal of dead eggs from the jars a long-distance siphon is 
used at Put-in Bay station, which saves much labor. It is constructed 
thus: To the short end of the ordinary siphon, which consists of a thin 
quarter-inch brass tube about a foot long bent into the form of a goose 
neck, is attached a j)iece of common rubber tubing 3 or 4 feet long with 
a finch interior diameter. This is connected with a rubber tube of the 
same size and long enough to reach the whole row of jars or all in the 



MANUAL OF FLSH-CULTURE. 127 

house if desired. The connection is made by a thin brass nipple with 
the same interior diameter as the piece of rubber tube to be joined by 
slipping it into the longer piece and lashing it on the outside with twine, 
leaving about three-quarters of an inch outside to slip into the shorter 
piece after the siphon is started. The other end of the long tube is 
connected with a like piece of brass tubing, bent to a quarter circle to 
prevent the rubber tubing from kinking, to and through the center of 
a wooden float some 12 inches in diameter and 1 or 2 inches thick. 
This is placed in a tub or large pail; the short siphon is started and 
connected as above described, and the long siphon is in working order. 
The water runs over the rim of the tub into the sluice, over which it is 
placed, and the eggs settle to the bottom. A whole hatchery can be 
operated without moving the tub, although it is better to raise it 5 or 6 
feet from the floor for the upper rows of the jars, as the suction 
otherwise becomes a little too strong and liable to injure the good eggs 
when passing too rapidly through the tube. 

For convenience and for economy of space and water, the hatching 
jars are arranged in tiers, constituting what is known as a "battery." 
The structure of a battery, with its complicated system of supply 
and waste troughs and with the jars and their attachments, is rather 
difficult to describe clearly, but may be understood by reference to 
plate 35, at the end of the volume. 

Each battery is divided into two sections, which have four rows of 
jars on each side, setting on shelves 3 feet apart. The water is admitted 
through an iron pipe to the uppermost cross-tank ; from there it runs 
into the uppermost supply-trough, which, like all the others, is 13 inches 
wide and 9 inches deep, inside measurements. The iron pipe is provided 
with a ball-cock, regulating automatically the supply of water. The 
supply-troughs are from 22 to 34 feet long, the upper ones being the 
shortest and the lower the longest. The first supply-trough has a row 
of brass cocks on either side taking the water 1 inch from the bottom. 
A half-inch rubber tube, 6 inches long and forming when adjusted a 
quarter circle, is slipped over the outer end of the cock and the upper 
end of the iron tube, which is inserted in the jar. The water flows from 
this upper supply trough, which may be called No. 1, in section No. 1, 
through the cock, rubber tube, iron tube, and jar, from which it is dis- 
charged into what may be called waste-trough No. 1, which is directly 
below supply-trough No. 1. This discharges its water into a cross-tank, 
the second from the top, which carries the water across to supply -trough 
No. 2, which is in section No. 2. This supplies the second of the eight 
rows of jars, through which all the water passes, and after passing 
through the jars, as before described, it empties into waste-trough No. 2, in 
section No. 2, which carries it to cross-tank No. 3, which in turn carries 
it across and delivers it to supply-trough No. 3, which is in section No. 
1. Thus the water goes back and forth from one section to the other, 
dropping a step at each passage, until it finally enters the fry- collecting 
tank on the floor, which is 3£ feet wide, 9 feet long, and 2 feet deep. 



128 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 

The cross-tanks are in steps, like a flight of stairs, which accounts 
for the unequal lengths of the supply-troughs. Each has an overflow 
in the center, over which a small amount of water is kept running, so 
that the attendant can see at a glance that all of the troughs are full. 
Screens are interposed at such places in the cross-tanks that the fry 
discharged into them through the waste-troughs can not enter the oppo- 
site supply-troughs, but will float with the overflow successively into 
the lower cross-tanks down to the fry-collecting tanks. 

The fry-collecting tanks, one for each battery, are connected with the 
main collecting tanks by means of 2-inch gas-pipe, fitted with valves, 
X>assing under the floor of the hatchery. The main tanks, eight in 
number, are 3 feet wide, 16 feet long, and 2 feet deep ; in these the fry 
are retained until dipped out for shipment or planting. 

The only marked difference between the method of operating the jars 
at Put-in Bay and other stations is the use of a finch iron gas-pipe, 
instead of a glass tube, for supplying the jars with water, and the addi- 
tion of a tin cone, 6 inches long and 1 inch in diameter at the lower 
end, which is soldered to the end of the iron pipe and reaches within 
one-eighth inch of the bottom of the jar. The tube is held in place by 
an iron bracket, fastened to the supply-trough and held by a thumb- 
screw. The cone has the effect of spreading the water^and giving an 
easier and more thorough motion to the eggs than can be obtained with 
a straight tube. 

At Put-in Bay the water passes through eight rows of jars, and the 
fact that the eggs in the lower rows of jars are just as good as those 
in the upper rows is proof of the practicability of the plan. 

The jars require 6 quarts of water per minute to each jar on the top 
row, this amount again supplying the successive tiers of jars on the 
shelves below. If -more jars are placed on the lower shelves than on 
the top one, a greater quantity of water must necessarily be added, 
equal to 6 quarts of water to each jar. 

The temperature of the water must, of course, with the large quan- 
tities used, be what nature makes it, but if much above 50° F. good 
results can not be expected with whiteflsh eggs. When the work 
begins, early in November, the temperature of the water in Lake Erie 
is from 40° to 50° E., while late in the month it is generally about 35° 
to 38°. As soon as the lake freezes over, or ice in any considerable 
quantity forms, the temperature of the water as it passes through the 
jars remains very uniform at 32£°. When the ice goes out, which is 
generally about the middle of March, it rises slowly, and when the fry 
begin to hatch, the latter part of the month, it is generally up to about 
33° or 34°. 

The jars, tubes, troughs, etc., should be kept scrupulously clean. 
The usual coating for the inside of troughs and tanks is asphaltum 
varnish, but a mixture of coal tar and turpentine has proved an excel- 
lent substitute. Eor the first coat on new wood equal parts of each 
are employed; for the second and third coats one-third turpentine and 



MANUAL OF FISH-CULTURE. 129 

two-thirds coal tar. The tar should be as warm as the touch will bear, 
and the turpentine, which should be pure, should be added slowly while 
the mass is being vigorously stirred. The mixture dries quickly and 
forms a hard, durable surface, which is entirely waterproof and much 
more lasting' than asphaltum ; it is also much cheaper, an important item 
in a large station. While applying it the tin pail in which it is mixed 
is kept in another and larger one partly filled with moderately hot 
water. For pitching the cracks and joints the best asphaltum pitch is 
used, softened with paraffin to the consistency of chewing-gum — that 
is, just so that it will not break in cold water. This pitch holds firmly 
to the wood and keeps its place in warm weather. Other pitches which 
have been tried will run in warm weather and get hard with use, 
breaking when cold. 

THE CARE AND PLANTING- OF THE FRY. 

When the fry hatch they immediately leave the jar and follow the 
course of the running water, some going through the succeeding jars, 
provided there are no screens interposed to prevent this, others through 
the overflows from the cross-tanks, until all reach the fry-collecting 
tank at the bottom, whence they are carried to the main collecting 
tanks. It has been urged by some that it is injurious for the fry to 
pass down through the lower jars with the complement of eggs, but in 
practice this has not been the case. 

An air -jet on the inside of the screens will prevent clogging by the 
accumulation of eggshells and impurities suspended in the water. This 
may be easily arranged by providing an air-pump and connecting with 
it a pipe carried along the side of each tank on the inside of the screen 
and thence at right angles parallel to the screen and about an inch 
distant. This cross-pipe should be perforated on one side with holes 
^2 inch in diameter and 3 inches apart, the holes opening toward the 
screen and upward at an angle of about 45°. When the air is turned 
on, an apparently solid mass of bubbles will arise along the whole sur- 
face of the screen. With this arrangement the screens will run hours 
or even days without any attention, whereas without the air-jet one or 
more men are employed keeping the screens clean, and many fry are 
unavoidably killed by being forced against the screens and by the work 
of the men in keeping them free. The thorough -aeration of the water 
thus indirectly accomplished is very beneficial when large numbers of 
fry are passing over, and double the number can be safely handled in 
troughs thus equipped. 

At Put-in Bay the fry are planted as soon as hatched. They are 
dipped from the fry tanks into kegs, in which they are transported to 
the natural spawning-grounds on the reefs; each keg containing 50,000 
to 100,000 fry, according to the distance to be traveled. If they are to 
be taken any considerable distance, fresh water is kept running on 
them. If the facilities are such that the fry can be held in tanks until 
they attain a length of an inch before being planted, they would be 

I\ O. K. 1897 9 



130 REPORT OF COMMISSIONER OF FISH AND FISHERIES.^ 

better able to take care of themselves than if deposited at an earlier 
stage. In the spring of 1896, about 1,000 whitefish fry were held in one 
of the station troughs until late in April, with no other food than the 
entomostraca and other minute life which came into the troughs with 
the water pumped from the lake. They grew considerably and were 
remarkably active. Cannibalism was of frequent though not of general 
occurrence; toward the close of the period through which the fry were 
held, numbers could be seen which had seized others by the tails and 
swallowed as much of the bodies as possible, which was, of course, but 
little. In every case one of the larger had attacked one of the smaller, 
the victim being dead and his destroyer swimming about actively with 
the body of the dead fry trailing along his side. If these fry had been 
regularly supplied with food, it is not probable that cannibalism would 
have occurred. 

REARING IN PONDS. 

There have been few attempts to raise whitefish in ponds on a large 
scale, but experiments lead to the belief that under favorable condi- 
tions whitefish can be raised in artificial ponds to some extent. Of 
course an abundance of good cold water, suitable ground for the con- 
struction of deep ponds, and convenience to railroad communication 
would be essential to success. 

A successful experiment in this direction was begun at Northville in 
1882. The fish were treated as young trout are, being fed wholly on 
liver. Three-year-old whitefish, artificially reared, yielded a large num- 
ber of eggs, a fair percentage of which were fertilized. Fish weighing 
from 3 to 4^ pounds, that had never been fed on anything but liver, 
were plump and healthy. Similar successful experiments have been 
made in Europe with one of the native whitefishes ( Coregonus lavaretus). 

The most noteworthy experiments in the rearing of whitefish in ponds 
have been conducted by private enterprise at Warren, Indiana. The 
following account of the work will be of interest: 

In 1890, 50,000 whitefish fry, obtained from the Sandusky station of the United 
States Fish Commission, were placed in a pond 20 by 40 feet, having a maximum 
depth of 5 feet. In November of the same year 864 whitefish, averaging 7-J or 8 inches 
in length, were taken from the pond. This result was not considered satisfactory, 
although the conditions were not favorable, as there was no natural food in the pond 
and no artificial food was regularly supplied, the fish feeding on various kinds of 
food thrown into the pond from time to time. The fish kept near the bottom, and 
were never seen from the time of planting to the time the pond was drawn. 

In 1891, half a million eggs obtained at Toledo were hatched with a loss of about 
30 per cent, and the resulting fry, together with a small number procured from Put-in 
Bay station, were planted in a pond containing the small whitefish previously men- 
tioned. This pond was 65 by 65 feet and 12 feet deep. It is supposed that practi- 
cally all the fry were devoured by the larger fish. Prior to the time of planting the 
young whitefish the older ones were very inactive and seldom seen, but as soon as 
the plant was made they became very active, and for a period of two weeks, about 
sunset, they could be seen leaping and darting up out of the water after the fashion 
of black bass chasing minnows. 



MANUAL OF FISH-CULTURE. 131 

In the following season the fry were placed in pens in a pond. Confervae formed 
in the ponds, clogging the screens, and the water got so warm that the fry, which 
were dying rapidly, were placed in the pond with the large fish. 

In 1893 the experiments were more encouraging. About 120,000 fry were placed in 
a new pond, 200 feet square and from 2-A- to 14 feet deep, supplied with 25 gallons of 
running water per minute at the lowest stage. Fifty thousand fry were held in a 
small tank at the hatchery, so that their habits, food, etc., could be studied. This 
afforded more instruction than all former experiments combined. Before the umbili- 
cal sac was absorbed tbe fry began to take the prepared food, and as soon as the sac 
was entirely gone they ate freely. They grew rapidly and did well until the middle 
of May, when, the weather being very warm, the temperature of the tank rose to 
63° F., resulting in the death of some of the fry and necessitating a removal of the 
remaining fry to the pond containing the other fry of the same age. These fry were 
from 1 to 1J inches long when put in the pond. They had been fed on nothing but 
very finely divided glutin, a product of wheat, of a yellowish-white color, very even 
in size and semi-buoyant. The floating property of this food is supposed to be very 
important, as the whitefish when young do not feed on the bottom, which is their 
habit when older. Any part of this food which settles on the bottom must be removed, 
as it is liable to ferment and rise to the surface, when, if the fry eat it, they will die. 

For the purpose of removing the fry to another pond the large pond was drawn in 
November of the same year in which they were hatched. A large seine was com- 
pletely filled with fish at the first haul. Being very deiicate, a great many were 
killed before efforts could be made to move them. It is estimated that nearly 50,000 
of these young whitefish were lost. They were from 7 to 9 inches long, being about 
8 months old. Several thousand were saved which are now (1895) 2-J years old. 
When 2 years old 70 were caught, which measured from 16 to 18 inches long. 

When the fry are about an -inch long they are fed on a stiff dough made of fine 
middlings. This food is placed on the bottom of the tank and all that is not 
consumed is removed. This is also the sole food of the adult whitefish. It is 
placed in water shallow enough so that the fish-culturist may see if it is all consumed 
during the night, the fish feeding exclusively at that time. If all is not eaten, a 
less quantity is given for the next day, as a matter of economy and to prevent the 
pollution of the water. 

It has been found that in the raising of fry the temperature of the water should 
not go above 55° F., and that 65° is fatal, while fish three or four months old will 
stand a much higher temperature. 



Report U. S. F. C. 1 897. (To face page 133.) 



Plate 36. 












IK"- '.■■ 




&■;; 






THE SHAD. 



DESCRIPTION OF THE SHAD. 

The shad (Alosa sapidissima) is the largest, best-known, and most 
valuable member of the herring family in the United States. The body 
is deep and compressed, the depth varying with the sex and spawning 
condition, but averaging about one-third the body length. The head, 
contained about 4| times in the body length, is quite deep; the cheek 
is deeper than long. The jaws are about equal, the lower jaw fitting 
into a deep notch on the tip of the upper. Teeth are present in the 
young, but are not found on the jaws in the adult. The eye is contained 
5| to 6 times in the length of head. The gillrakers are long, slender, 
and numerous, there being from 93 to 120 on the first arch. The fins 
are small and weak, the dorsal containing 15 rays and the anal 21. 
The lower edge of the body is strongly serrated, the plate-like scales 
numbering 21 before the ventral fin and 16 behind it. The scales in 
the lateral line number 60. The body is dark-bluish or greenish above, 
silvery on the sides, and white beneath. There is a dark spot behind 
the gill-opening and sometimes a row of smaller spots along the side. 
The vertical fins often have black or dusky edges. The peritoneum 
is white. Supposed structural and color peculiarities in shad from 
different regions or basins have not been verified. 

Prom the other clupeoids with which the shad is frequently asso- 
ciated in the rivers, it may be readily distinguished. In all of them the 
cheek is longer than deep. The hickory shad or hickory jack (Pomolobus 
mediocris) has a j)rojeeting lower jaw and a very straight profile. The 
river herrings or alewives are much smaller than the shad, have fewer 
and shorter gillrakers, and a larger eye (3£ in head). In the branch 
herring (P. pseudoharengus) the peritoneum is pale, while in the glut 
herring (P. cestivalis) it is black. 

The female shad is larger than the male, the average difference in 
weight being more than a pound. The mature males taken in the 
fisheries of the Atlantic coast weigh from 1^ to 6 pounds, the average 
being about 3 pounds; the females usually weigh from 3 to 6 pounds, 
the average being 4f pounds. The general average for both sexes is 
between 3| and 4 pounds. In the early history of the fisheries, shad 
weighing 11, 12, and even 14 pounds were reported, but 9-pound shad 
are very rare on the Atlantic coast, and 10 pounds seems to be the 
maximum. Some seasons an unusual number of large shad (7 to 9 
pounds) appear in certain streams. On the Pacific coast shad average 
a pound or more heavier than on the Atlantic, occasionally attaining a 
weight of 14 pounds ; many have been reported weighing 9 to 12 pounds. 

133 



134 EEPORT OF COMMISSIONER OF FISH AND FISHERIES. 
DISTRIBUTION AND ABUNDANCE. 

The shad is distributed along the entire east coast of the United 
States, and northward and eastward to the Gulf of St. Lawrence. It 
has gradually spread from the Sacramento River, California, where it 
was introduced by the California Fish Commission, and is now taken 
from southern California (Los Angeles County) to southeast Alaska. 
In the early history of the country its abundance excited unbounded 
astonishment. Nearly every river on the Atlantic coast was invaded in 
the spring by immense schools, which, in their upward course, furnished 
an ample supply of good food. Notwithstanding greatly increased fish- 
ing operations and the curtailment of the spawning-grounds, the supply 
in recent years has not only been generally maintained, but owing to 
fish-cultural efforts has been largely augmented in certain streams, 
notably in the Kennebec, Hudson, Delaware, Susquehanna, Choptank, 
Potomac, Nanticoke, Rappahannock, York, James, Chowan, Roanoke, 
Neuse, and St. Johns rivers, and in Chesapeake Bay, Albemarle Sound, 
Croatan Sound, and Pamlico Sound, and the Sacramento and Columbia 
rivers. 

SHAD IN THE OCEAN. 

The shad passes most of its existence at sea, and little is known of 
its habits and movements when out of the rivers. The ocean areas to 
which it resorts are unknown, and what its salt-water food consists 
of has not been determined. In the Gulf of Maine it is known to 
associate in large numbers with mackerel and herring during the 
months of June, September, and October, being most numerous in June. 
It has been taken at North Truro, Massachusetts, in the fall, when the 
ocean temperature was from 43° to 49°. In the month of November, 
one year after another, it has been found on the west side of Sakonnet 
River, Rhode Island. In May and June it has been captured with 
mackerel a few miles northeast of Cape Cod Light. Some instances 
of capture indicate that under certain conditions the adults may 
remain in the fresh-water rivers a whole year. In November, 1890, 600 
were taken in the Chesapeake Bay. It has been found in the Potomac 
in considerable abundance in August and September, and even during 
the last week in December. Its movements are largely controlled by 
the water temperature. It is believed that it aims to occupy a hydro- 
thermal area of certain temperature; that its migrations are determined 
by the shifting of this area, and that this temperature is between 00° 
and 70°. 

SHAD IN THE RIVERS. 

The annual migration of the shad from the ocean to the rivers is 
for the sole purpose of reproduction. It ascends to suitable spawning- 
grounds, which are invariably in fresh water, occupying several weeks 
in depositing and fertilizing its eggs in any given stream. 

Its migrations from the sea are in quite a regular succession of 
time with relation to latitude. It first appears in the St. Johns River, 



MANUAL OF FISH-CULTURE. 135 

Florida, about November 15, the season of greatest abundance being 
February and March. In the Savannah Eiver, Georgia, and the Edisto, 
South Carolina, the run begins early in January and ends the last of 
March. In the North Carolina rivers these stages of the migration are 
a little later. In the Potomac Eiver advance individuals appear late 
in February, but the fish is most numerous in April. In the Delaware 
Eiver the maximum run is about the 1st of May. It reaches the Hud- 
son Eiver the last of March, and is found in the Connecticut toward 
the end of April, is most abundant the last of May, and leaves the 
stream late in July. In the Kennebec and Androscoggin rivers, Maine, 
it is first taken in April and has left by the middle of July. In the St. 
John Eiver, New Brunswick, it appears about the middle of May, and 
in the Miramichi Eiver, New Brunswick, late in May. 

The main body of shad ascends the rivers when the temperature of 
the water is from 56° to 66°, the numbers diminishing when the tem- 
perature is over 66°. Successive schools enter the Potomac from 
February to July, the males preceding the females. Of 61,000 shad 
comprising the first of the run received at Washington, D. C, from 
March 19 to 24, 1897, 90 per cent were males. Toward the close of the 
season males are extremely scarce. 

The movement of the shad up the rivers is not constant, but in 
waves, causing a rise and fall in the catch. In some of the rivers the 
fishermen claim that a fairly well-defined run occurs late in the season, 
consisting of a somewhat different fish, known as "May shad." 

The erection of impassable dams along the rivers and streams was 
probably the first thing to curtail the natural spawning-grounds of 
these fish and to seriously check their natural increase. 

As shad enter the rivers only for the purpose of spawning, the 
fisheries are necessarily prosecuted during the spawning season, and 
often upon the favorite spawning-grounds. The increase of population 
necessitates a larger supply of fish and requires the use of more 
apparatus, and the number of shad that reach fresh water is therefore 
greatly curtailed by assiduous fishing with all kinds of contrivances in 
the estuaries and in the mouths and lower parts of rivers. Under these 
conditions of a restricted spawning area and increased netting shad 
would soon be exterminated without artificial propagation ; or the fish- 
ery, at least, would greatly diminish and become unprofitable. Such a 
crisis was fast approaching in 1879, when the Fish Commission entered 
upon systematic work in shad propagation. 

From their birth until their return to the rivers shad are preyed 
upon incessantly by other fish, so that the larger portion of the young 
do not survive their few months' sojourn in fresh water, and of those 
which leave the rivers each season probably not one in one hundred 
reaches maturity to deposit its eggs and contribute to the perpetuation 
of its species. In the rivers striped bass, white perch, black bass, and 
other predaceous fishes devour the young, and when they reach salt 
water, sharks, horse-mackerel, kingfish, etc., undoubtedly destroy many 



136 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 

adults. It has been observed by North. Carolina porpoise fishermen 
that as the shad swim close along the shore the porpoises follow and 
feed on them till they pass into fresh water. In the rivers the adult 
shad is comparatively free from enemies. 

To what extent the pollution of the waters has reduced the numbers 
of shad is not known, but acids, sawdust, garbage, oils, gas tar, and 
refuse from dye-works all tend to make the water of rivers unsuitable 
for them. 

FOOD. 

After entering the rivers, the shad takes but little, if any, food 
previous to spawning, but after casting its eggs it bites at flies or any 
small shining object, and has been known to take the artificial fly. 
The mouth of the adult is practically toothless, and its throat contains 
no functionally active teeth. The water which passes through the 
branchial filter — the gillrakers — is deprived of the small animals which 
are too large to pass through its meshes. It is a common remark with 
fishermen and others that food is rarely found in the stomach of the 
adult shad in fresh water, but examinations have shown that the shad 
does, in some instances, eat small Crustacea, insects, etc. The only 
substance commonly found in its stomach in fresh water has the 
appearance of black mud. It is held by some that the shad swims 
with its mouth open and may unintentionally swallow the small organ- 
isms found in its stomach under such circumstances, but as far as 
observation of fish in aquaria and experiences of net fishermen go, the 
shad does not swim with its mouth open. 

NATURAL SPAWNING. 

Shad are liable to be ripe anywhere above brackish water, and under 
favorable temperature conditions spawn wherever they happen to be, 
but in some river basins they exhibit a well defined choice of sj>awning- 
places, preferring localities below the mouths of creeks, where the 
warmer water of creeks mingles with the colder channel water. The 
shad lays its eggs during the highest daily average temperature, a con- 
dition realized about sunset, when the warmer shoal water commingles 
with the colder channel water, establishing a balance. The principal 
spawning occurs from 5 p. m. to 10 p. m. Observations on the Potomac 
Eiver show that of the eggs from shad caught in a seine only 11 per 
cent were taken between midnight and noon, the percentage in the 
morning being 14 one year and 8 another. 

The eggs in the ovaries remain in a compact mass until they ripen, 
at first occupying but a small space, but gradually increasing until 
they distend the whole abdomen, the average weight of the ovaries being 
about 13 ounces. Close examination at the approach of the spawning 
time will disclose large maturing eggs of rather uniform size and others 
smaller and of variable size. Whether the latter are the forming eggs 
for the next year, for two or three succeding years, or for the lifetime of 
the fish has not been determined, nor is it known whether shad spawn 
every year. The small and shrunken ovaries of a spent fish are still 



Report U. S. F. C. 1897. (To face page 136.) 



Plate 37. 




A. Freshly extruded egg enlarged, showing its envelope much wrinkled and its surface covered with 
small round vesicles. 

B. Shad egg, showing vitellus and distended egg-membrane, natural size. 

C. Shows the gradual accumulation of germinal matter at one pole of egg, the polar prominence ex- 
ternally, and presence of plasmic processes extending down through the vitellus. 

D. Enibryo shad in its natural position in its spacious enveloping membrane. From a photograph. 

E. Diagrammatic representation of an embryo to show course of segmental ducts sd and extension 
outwai'd of pectoral plates pp, which are intimately concerned in the development of pectoral fins. 

F. Side view of a young shad 13 days old, viewed as a transparent object, ab, rudimentary air- 
bladder: i, liver; Gb, gall-bladder. 

G. An embryo in its envelope, on the third day of development, nearly ready to hatch. 



Report U. S. F. C. 1 897. (To face page 1 36.) 



Plate 38. 




H and I. Two views of an egg after the blastoderm has spread considerably and the embryonic area e is 
well defined. 

-ST. View of nnhatched embryo, which developed in a temperature of 45° F., producing distortions of tail 
and notochord. 

L. An egg-envelope with its contained embryo, forty-four hours after impregnation, viewed as a trans- 
parent object. 

M. An eg-g-envelope with its contained embryo at the beginning of the third day of development. From 
a photograph. 

N. Anterior portion of a young fish on fourth day. To show relations of liver L to yelk Y", over which 
the portal vessel pv passes forward to empty into the venous sinus, in common with the anterior and 
posterior jugulars,/' and,/, ba bulbus aorta?, ve ventricle. 

O. View of fore part of a young fish 17 days old, from ventral side. 



Roport U. S. F. C. 1897. (To face page 136.) 



Plate 39. 




P. Young fish immediately after hatching, viewed as an opaque object and somewhat obliquely from one side, 
to display the relations of branchial and hyomandibular arcnes, and position of pectoral fin. 

Q. Young fish third clay after hatching, viewed as a transparent object to show extension of segmental duct 
forward; chorda ch, and liver L. 

B. Young fish 5 days after hatching, very much enlarged, and viewed as an opaque object. Only a slight rem- 
nant of the yelk-sack Y remains. 

S. Young fish IT days after hatching, viewed partly as an opaque and partly as a transparent object; py pylorus 
and rudimentary air-bladder above it; I intestine, filled with the remains of ingested food. The opercula are 
already so far developed as partly to conceal the branchiae. 



MANUAL OF FISH-CULTURE. 137 

found full of these eggs of different sizes. Shortly before spawning, 
transparent eggs of large size, contrasting strongly with the opaque 
golden hue of less mature ones, will he found scattered through the still 
compact ovarian mass, and becoming more and more numerous, the 
ovaries disintegrate, the eggs fall apart, and extrusion begins, a liquid 
stream of eggs and mucus flowing from the oviduct on the slightest 
pressure of the abdomen. 

Freshly deposited shad eggs are of a pale amber or pink color, and 
are transparent. They are about -^ inch in diameter and somewhat 
flattened and irregularly rounded in form. The egg membrane is much 
wrinkled and lies in close contact with the contained vitellus, Imme- 
diately after fertilization the egg becomes spherical through the absorp- 
tion of water and apparently gains very much in bulk, measuring from 
£ to j inch in diameter; but this gain is only the distended egg mem- 
brane, the vitellus or true germinal and nutritive portion not having 
increased. The vitellus is heavier than water, and a large space filled 
with fluid now exists between it and the membrane, the vitellus rolling 
about and changing its position as the position of the egg membrane is 
altered. No adhesive material is found on the outside of the membrane, 
though when first extruded the eggs are covered with a somewhat sticky 
ovarian mucus. 

In a state of nature the shad deposits its eggs loosely in the rivers 
without building a nest, the two sexes running along together from 
the channel towards the shore, and the eggs and milt being ejected 
simultaneously. On quiet evenings, at the height of the season, 
spawning shad may be heard surging and plunging along the shores. 
By fishermen this is termed "washing." 

Shad are very prolific, but much less so than many other food-fishes. 
The quantities of eggs taken by spawn-takers do not represent the 
actual fecundity, for many are cast in advance of stripping. The 
average number is not more than 30,000. Single fish have been known 
to yield 60,000, 80,000, 100,000, and 115,000 eggs; and on the Delaware 
River, in 1885, one yielded 150,000. Many eggs fail to be fertilized, 
and but a comparatively small percentage of those impregnated are 
hatched. After being extruded, the eggs sink to the bottom, where 
they remain until hatched, subject to the attacks of fish and other 
water animals. Eels are very destructive to shad spawn and often 
attack shad caught in gill nets, devouring the undeposited eggs and 
sometimes mutilating half the catch of a gill net fisherman. 

The development of fungus is one of the greatest dangers to shad 
eggs in a natural state, and another potent agency for their destruction 
is the mud brought down by heavy rains, burying and suffocating 
the eggs. 

After spawning, shad are denominated "down-runners," "racers,'' 
and "spent fish." They are then very lean and hardly fit for food, but 
they begin to feed and have become fatter by the time they reach salt 
water in the summer or fall. 



138 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 

YOUNG SHAD. 

In the Middle States the young fish remain in the rivers, feeding 
and growing, until the cool weather of fall comes on. They then 
begin to drop downstream, and by the last of November have passed 
out into the ocean or bays, and are lost sight of until they come back 
three or four years after, full-grown and ready to spawn. They leave 
the Potomac River when the water falls to about 40°. By that time 
they are about 3 inches long. For the last two or three years they 
have been observed in great abundance about Bryan Point, feeding and 
jumping out of the water about sunset. They keep within the open 
streak of water between the shores and the water- grass which covers 
the flats, in water 2 to 5 feet deep. After mild winters young shad have 
been found in the Potomac River in April, 30 miles above brackish 
water and 160 miles from the ocean, associated with young alewives and 
sturgeon. Some immature shad, apparently 2 years old, are caught 
each year in seines operated in the fresh water of the Potomac River, 
and undersized shad are frequently caught in the New England rivers, 
where the tidal waters are of little length. 

COMMERCIAL VALUE. 

The shad is one of the most palatable and popular of fishes. Its 
flesh is rich, but not oily, and the roe is considered a delicacy. It is 
the most valuable river fish of the Atlantic coast, and, next to the 
Pacific salmon, the most important species inhabiting the fresh waters 
of North America. In every Atlantic State from New Jersey to Florida, 
inclusive, it is the most valuable fish, and in New York it is second only 
to the bluefish. Among all the economic fishes of the United States 
only the salmon and cod exceed it in value, and, considering all branches 
of the fishing industry, only the whale fishery and the oyster fishery, 
besides the foregoing, are financially more important than the shad. 

In 1896 the shad catch of the Atlantic seaboard numbered 13,145,395 
fish, weighing 50,847,967 pounds, and worth to the fishermen $1,656,580. 
The value of the shad catch of the Pacific States in 1895 was $5,600, a 
sum representing 366,000 pounds. 

EARLY ATTEMPTS AT SHAD-CULTURE. 

The systematic development and extension of shad-culture were 
undertaken with the definite purpose of testing the value of artificial 
propagation in maintaining an important fishery which was being 
rapidly depleted. As early as 1848 shad eggs were artificially taken 
and fertilized, and in 1867 more extensive experiments were made on 
the Connecticut River, and later on the Potomac, with encouraging 
results. The attention of many States was thus attracted to the work, 
and in 1872 it was taken up by the general government. Prior to the 
experiments on the Connecticut, certain species of the salmon family 
had been principally dealt with in fish-culture, and different methods 
from those in use were necessary for shad-hatching, owing to the less 
specific gravity of shad ova and the much shorter period of time 
required for the development of the fish from the egg. 



MANUAL OF FISH-CULTURE. 139 

The "Seth Green box," a modification of the floating-box used for 
batching trout and salmon eggs, was first tried with great success, but 
floating-boxes were subject to various accidents when used in tidal 
waters, and in rapid succession devices of various kinds were brought 
forward to supplant them. The most important were hatching-cones 
and the plunger-buckets, which, though imperfect, rendered larger 
operations possible. At this period the apparatus was arranged on 
flat-bottomed barges and towed from point to point along the coast from 
Albemarle Sound to the Susquehanna Eiver, a slow and expensive 
method. The Chase whitefish jar worked with considerable efficiency, 
but required modifications, and finally the " universal" hatching jar now 
in use was adopted in 1882. 

During the years of experimental work from 1872 to 1880, 97,471,700 
shad fry were planted, beginning with 859,000 in 1872, while in 1880, 
28,626,000 were distributed. Prior to 1880 deposits of a few hundred 
thousand each were made in as many different streams as possible, but 
the increased production of young fish made it possible to ship and 
plant the fry by the carload, and by 1881 shad-culture was established 
on a large scale, barge operations were abandoned, and the work 
conducted on shore. The basins of the Chesapeake Bay and Delaware 
River had meanwhile been selected by the United States Commission 
as the natural seat of operations, though the State commissions from 
Massachusetts to South Carolina were actively engaged on their own 
account. At present the States, except Connecticut, New York, Penn- 
sylvania, and Maryland, have practically abandoned shad-hatching, 
leaving the work to the general government. 

EGG-GROUNDS. 

Every river on the Atlantic coast from Massachusetts southward has 
been examined by the agents of some State commission or the United 
States, or by both, in order to determine the natural spawning-grounds 
of the shad. On nearly every stream hatcheries have been operated 
at one time or another, but usually eggs were not obtained in sufficient 
numbers to justify continued operations, except in the Chesapeake and 
Delaware basins. However, it is not unlikely that after further investi- 
gation it will be found practicable to maintain hatcheries on rivers 
which have long since been abandoned. It is certain that work on the 
Albemarle Sound can be successfully conducted, and though operations 
on the Hudson River have not been on a large scale, better results may 
be there obtained in the future. 

In certain river stretches, apparently favorable, no ripe fish are found ; 
for example, in the Roanoke River for 15 miles above its mouth, where 
10,000 to 15,000 shad are taken annually, mature eggs can not be found, 
though the fish spawn just below there, as they do many miles above at 
Weldon. In the Sutton Beach seine, the one in North Carolina waters 
which has afforded the most spawn, only about one spawning shad to 
each 100 is caught, and the annual catch of this seine is 30,000 to 75,000 
per annum. In view of such facts, it is not remarkable that difficulty 



140 REPORT OP COMMISSIONER OP FISH AND FISHERIES. 



has been experienced and time consumed in deciding on permanent loca- 
tions for hatcheries. 

The spawning period varies widely in different seasons ; in some years 
shad are numerous and in spawning condition two or three weeks after 
the time when they have ordinarily disappeared. They deposit eggs at 
some point along the coast for six continuous months. 

The following streams have been occupied by hatcheries, as some of 
them are now, and it will be observed that the approximate spawning 
periods, beginning early in the South, become gradually later toward 
the North. 



Waters. 


Place. 


Period. 




Jacksonboro, S. C 


Mar. 5-26. 

Apr. 1-30. 

Apr. 15 to June 10. 

Apr. 17 to June 15. 

May 10 to June 20. 

May 15 to June 30. 

Do. 
June 15 to July 5. 
June 1 to July 15. 






Below Washington, D. C 

Below Havre de Grace, Md ... 
Gloucester, N. J 














Holyoke, Mass 









The United States Fish Commission operates stations at Bryan 
Point, 12 miles below Washington on the Potomac, and at Battery 
Island at the mouth of the Susquehanna, while the steamer Fish Haivk, 
fitted up as a floating hatchery, is engaged during the shad season on 
the Delaware Biver. These two stations and the vessel can receive 
respectively 16,000,000, 40,000,000, and 12,000,000 eggs. On more than 
one occasion each -has been taxed to its utmost capacity, bat as the 
average hatching period is 8 days, and three of the special cars of the 
Commission are hatcheries in themselves and capable of taking 2,000,000 
to 4,000,000 eggs aboard at a time, the hatcheries can be quickly relieved 
in case of emergency. 

In 1896 the total number of the shad eggs collected was 149,822,000, 
yielding 93,481,500 fry. In 1897, owing to expansion of operations at 
old stations and prosecution of work in new waters, 205,000,000 eggs 
were taken, from which 134,545,000 fry were hatched. The aggregate 
number of shad fry planted by the Commission to and including the year 
1897 was over 1,375,000,000. 

The methods herein described are those in use on the Potomac, where 
the eggs collected at Bryan Point are shipped to Washington and there 
hatched in Central Station. 

Potomac Biver. — The Potomac Biver, immediately adjacent to Port 
Washington (12 miles below Washington, D. C), is probably more pro. 
ductive of ripe shad than any other area of the same size. This was 
discovered as early as 1880, and a station was soon developed there with 
steam pumps, tank, and hatching vessels. The seine operated at this point 
between 1887 and 1891 furnished 23 per cent of all eggs from the river.. 



MANUAL OP FISH-CULTURE. 



141 



In March, 1892, the station was removed 2 miles lower down the 
river to Bryan Point, on the Maryland side, opposite Mount Yernon. 
As the eggs can be more safely and economically transported than the 
fry, they are promptly transferred to Central Station at Washington, 
where the hatching is done, and the fry are sent out to the various 
rivers on the cars of the Commission, a side-track at Central Station 
permitting them to be brought close up to the building. 

The following table, taken from the records of the station, shows the 
value of the spawning-grounds: 



Tears. 


Number of 
eggs taken. 


Tears. 


Number of 
eggs taken. 


1880 


20, 749, 000 
43; 200, 000 
21, 800, 000 
24, 274, 000 
19, 000, 000 
22, 576, 000 
36, 362, 000 
59, 435, 000 
81, 177, 000 


1889 


58, 233, 000 
35, 202, 000 
32, 980, 000 
13, 446, 000 
9, 423, 000 
32, 393, 000 
66, 065, 000 
64, 788, 000 
39, 707, 000 


1881 


1890 


1882 


1891 


1883 


1892 


1884 


1893 

1894 


1885 


1886 

1887 

1888 


1895 


1896 


1897 







In 1889 immense collections of eggs were made on certain days — 
8,368,000 on May 6 and 6,311,000 on May 7, and during seven days there 
was an average of over 5,000,000 per day. This was before and just 
after a freshet. 

To increase the supply of eggs, seine fishing has been attempted by 
the United States Fish Commission on both the Susquehanna and the 
Potomac, but the efforts were only partially successful and were finally 
abandoned. The extension of egg-taking by seines can not be relied 
upon, especially as this method of fishing has been declining for many 
years, owing to its greater expense, and a corresponding growth has 
taken place in the gill-net fishery. It is often difficult to obtain the 
ripe eggs from a seine on account of the great numbers of alewives 
taken at the same time. 

The following comparative table shows the shad-egg production from 
a Potomac Elver seine, together with the rjroportion of males, females, 
and spawning fish, and the number of eggs per fish : 



Tear. 


Total 
number of 

eggs 
obtained. 


Total 
ripe 
fish. 


Total 

shad 

caught. 


Per cent 

of 

males. 


Per cent 

of 
females. 


Average 
number 
of eggs 
per fish 
spawned. 


Per cent 
ripe. 


1887 


20, 956, 000 
22, 657, 000 
17, 738, 000 
10, 262, 000 
5, 276, 000 


652 

688 
612 
468 
228 


10, 348 

11, 212 

6,217 
4,606 
3 138 


71.4 
69.2 
52.3 
54.3 
57.1 


28.6 
30.8 
47.7 
45.7 
42.9 


32, 100 
32, 900 
28, 980 
21, 900 
23, 140 


6.3 
6.1 

9.8 
10.1 

7.2 


1888 


1889 


1890 


1891 


Average . 




15, 377, 000 


530 i 7,104 


60.8 


39.2 


27, 800 


7.4 



142 REPORT OF COMMISSIONER OP FISH AND FISHERIES. 

Had all other fisheries furnished an equal percentage of eggs, the 
annual Potomac collections would have reached about 300,000,000. 
But while the Fort Washington seine, with a catch of 10,000 shad, gave 
20,000,000 eggs, and another, capturing 18,000, gave 17,000,000, a third 
catching 60,000 shad, gave only 1,000,000. 

Eggs taken by gill fishermen are usually superior to those from seines, 
and the gillers attach enough value to the market for eggs to save 
almost all within reach. At the commencement of the season many of 
them secure spawning-pans, which they keep in their boats, taking and 
fertilizing the eggs themselves, and when accidentally overlooked by 
the regular spawn-takers they sometimes row several miles to bring- 
in pans of eggs. In 1896 a giller who laid out his net with the special 
object of securing spawning shad, caught 3,300 fish and sold over 
6,000,000 eggs to the Commission. About 1,100 of his fish were roe 
shad; of the total, about 6 per cent were ripe; of the 1,100 roe, about 
20 per cent were ripe. 

The average catch of shad by the gillers who supply eggs is 1,600 to 
1,800 per season; but they do not all operate specially for the capture 
of spawning fish, though this work is profitable and gillers are fast 
turning attention to it. The Fort Washington gilling boats furnish on 
an average about 1,000,000 eggs each a season, those at White House 
400,000, Sandy Bar 350,000, Green way 300,000, and Oraney Island 
150,000, the average being about 500,000 per boat. 

Susquehanna River. — The shoal water in the neighborhood of Battery 
Station is an extensive and valuable spawning-ground. The station 
is conveniently situated on an island and the possibilities in egg- 
collecting appear to be almost unlimited. Hundreds of gill fishermen 
are engaged and large seines are operated within easy distance. In 
1886 the station was overrun with eggs; 170 universal hatching-jars 
and 58 cones would not contain them, large numbers being held in 
cylinders, buckets, and pans. In 1888 over 105,000,000 were taken, 
and in 1889 7,600,000 were obtained in one night. Both egg- collecting 
and hatching are carried on, and the establishment is complete in itself. 
There is no transfer of the eggs except for occasional car shipments, 
and the fry are carried to Havre de Grace in 10-gallon cans for railroad 
transfer to the places of deposit. 

The collections at this station amounted to 45,983,000 eggs in 1896 
and 71,000,000 in 1897. 

Delaware River. — The steamer Fish Haivk has been employed in shad- 
hatching on this river nearly every season since 1887, the egg-collecting 
and other labor being performed by the crew. An interesting feature of 
the work is the large yield of eggs per fish. Eggs from this river have 
been saved regularly since 1887 from seines, but the available product 
among the gill fishermen has never been fully ascertained. 

The eggs collected by the Fish Hawk numbered 37,8*4,000 in 1896 
and 66,708,000 in 1897. 



Report U. S. F. C. 1897. (To face page 143.) 



Plate 40. 




MANUAL OP FISH-CULTURE. 143 

EG-G-COLLECTING. 

Collecting eggs is the work of experienced watermen, who must be 
prepared to endure all kinds of weather in open boats. The boats are 
towed out to the fishing-grounds by steam-launches, where the spawn- 
takers visit the nets of the market fishermen, obtaining from them the 
spawning fish. After eggs have been obtained a ticket is dropped into 
each panful, with the date and the name of the fisherman, for entry on 
the books of the station. The price for eggs is always above the 
market price of the shad, and payment is made at the end of the season 
on the basis #f 28,000 to the liquid quart, the price being $10 to $20 per 
1,000,000. On the Potomac 10 to 50 spawn-takers are employed at the 
station, besides 12 or 15 men who are engaged as hatching attendants, 
machinists, firemen, and cooks. 

The spawn-taker uses a 16-foot flat-bottomed bateau and is provided 
with a lantern, six small and four large spawn pans, and a dipper of 
1-quart capacity. The pans are made of tin and are of two sizes, 
11-inch and 18-inch diameters, the latter with handles. The smaller are 
for receiving eggs on delivery from the fish, and the larger for carrying 
them. The pans are thoroughly washed each night after use and not 
allowed to become rusty or indented. The dippers are round-bottomed, 
hold nearly a quart, and have handles with open ends, with 5 inches of 
the free end wrapped with seine twine. To obtain eggs from a seine, 
double the above number of spawn vessels may be required. 

Spawn-taking tubs of indurated wood fiber have been introduced in 
Potomac Eiver operations and found superior to tin, being without 
hoops or joints, non-corrosive, and non-conductors of heat. They have 
wood covers which fit inside the rims, and the tops fit tightly by means 
of a soft rubber joint: 4 inches of the central part of the cover is cut 
away to admit air. 

As the shad manipulated are sold and consumed in a fresh state, 
fishermen waste no time in transferring them to market boats, which 
are in waiting, and rapidity of execution is therefore required on the 
part of the spawn-taker, who must be alert and exact in hfs methods. 

In gill-net fishing there is usually ample time to assort the fish, 
which are taken into the boat one at a time, except when sudden 
squalls or exceptional captures force the premature hauling in of the 
net with the fish wound up in the meshes. Unskilled spawn-takers 
are liable to the mistake of stripping eggs without having the neces- 
sary milt to impregnate them, for several spawners may be taken over 
a period of ten or twenty minutes without the capture of a male fish. 
In such cases (of great frequency late in the season) the female fish " 
must be placed conveniently, backs down, to prevent the eggs from 
running out, and the males may have to be obtained from other boats. 
When ripe shad are taken in seines, two or three large baskets should 
be in readiness to receive them. 

Sometimes the number of ripe fish will be sufficient to occupy all the 
attention that can be devoted to them ; at other times the run of fish 



144 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 

is greatly reduced by local conditions. Even when other conditions 
are satisfactory, if neither high nor low water occurs about sunset but 
few ripe fish are caught. The large seines land toward the last of the 
ebb tide, and gill net fishermen can do nothing except on the change of 
the tide — on slack water. The fish spawn at a certain time of day, 
and when taken at other hours are not in spawning condition. Thun- 
derstorms sometimes occur for days in succession about sunset, the 
very hour when most disastrous. 

A scarcity of male fish toward the end of the season often cuts short 
operations when eggs, are plentiful. Unsuccessful attempts have 
been made to capture the males at such times by using gill nets with 
meshes smaller than those in the nets of market fishermen. Attempts 
have been made to pen the adults, but without success, as the fish 
become diseased and their eggs spoil within them. In gill nets the 
adult is entangled in the mesh and can not escape by struggling, and 
it therefore remains comparatively quiet. 

The quality of shad eggs is generally impaired where the fish are 
held for an hour or more in trap nets or seines. The eggs from fish 
taken in large seines are usually of bad quality, but those from short 
seines, which are landed quickly after the fish have been surrounded, 
are usually good; and those from trap nets, in which the fish have been 
hejd for some hours, are valueless. Eggs are rarely susceptible to fer- 
tilization longer than 20 minutes after the fish are taken from the water, 
though there are exceptions to this rule. On May 23, 1895, Potomac 
shad were stripped which had been out of the water about 1^ hours; 
they were kept separate, and at the end of 48 hours produced 100,000 
eggs, which yielded 98,000 fry. 

The shad dies very quickly after'capture and is immediately respon- 
sive to electrical storms, the catch of seines and nets of all kinds falling 
off promptly when a thunderstorm develops. Even in seines already 
laid out in the water, with lead line on the bottom, there is an appre- 
ciable decrease in such event. On the Delaware Eiver, May 29, 1887, 
nearly 50 per cent of the shad eggs on board the steamer Fish Hawk 
perished during an electrical storm which continued from 6 p. m. to 
midnight. There were 4,481,000 eggs with embryos well formed, and 
without perceptible change in water temperature 1,918,000 were killed, 
many turning white by 8 p. m. 

Heavy freshets cause an abrupt suspension of fishing, but the effect 
of a single freshet is usually temporary. The shad which have gone 
above are backed down before the muddy water, but reappear upon its 
outward passage. An occurrence of this kind will effect a great 
increase in egg receipts if the water temperature before muddy water 
comes is suitable. The shad that were scattered above being thrown 
back in a body, reascend in a body. 

A season of clear water is undesirable both for fishermen and hatching 
work, as the fish see the nets and avoid them, gill nets being put out 
only on the night tide and half the fishing being thus lost. The water 



MANUAL OF FISH-CULTUEE. 145 

should be discolored enough to prevent the fish from seeing the nets, 
but not thick, say from 10 to 20.* An occasional freshet reduces the 
temperature and prolongs the season ; however, with an equal number 
of fish in the rivers, clear water is probably more advantageous for 
natural increase, as a large proportion of naturally deposited eggs must 
perish from suffocation under the mud in seasons of freshet. 

THE WEATHER AND SPAWN. 

The development of eggs within the ovaries is hastened by heat and 
retarded by cold. In a warm season fish ready to spawn are more 
numerous early in the season than in a cold one, and the period for 
obtaining them is apt to close earlier. The eggs, not only after they 
aredeposited and impregnated, but before they leave the body of the fish, 
are affected by the temperature of the water, often being "blighted" 
or "rotten ripe." This phenomenon was observed as far back as 1873. 
It occurs on the water reaching 80° to 81°, or with a rapid rise. On 
the other hand, a sudden fall in temperature has been observed to 
arrest natural spawning, produce blighted eggs, and to destroy those 
in the hatching-vessels. Continued low temperature is also disastrous 
to fishing. 

An abnormally inferior quality of the Potomac Eiver eggs was noticed 
during the full period of operations in 1896. The bulk of the run of shad 
made their appearance on a rapidly ascending temperature, and the 
eggs were injured within the parent fish, more than half perishing 
before conversion into fry. The rise in temperature was greater than 
had been recorded in the eleven years preceding. The run of shad 
increased proportionately, the catch at one seine increasing from 100 
t® 800 in 21 hours. A snowstorm on April 7 — morning air temperature 
35° F. and mean air temperature 46° — was followed by heavy frost on 
April 9, the morning air temperature on the last-named date being 34°. 
The river water on April 10 was 46°, rising to 48° on April 12 and to 
71° in the afternoon of April 21, thus gaining 25° in 10 days. After 
April 21 the catch of shad fell off to such an extent that fishing was 
no longer profitable. 

The water of the Potomac early in March is usually of a temperature 
of 36° to 40°, rising to 52° to 58° about the middle of April, when the 
spawning period begins, and at the end of May, the close of the period, 
it averages from 65° to 70°. 

STRIPPING AND FERTILIZING THE EGGS. 

In stripx>ing the eggs the shad is lifted with the right hand and 
caught above the tail with the left. All slime and loose scales are 
removed by going over the fish two or three times in quick succession 
with the right hand. The head is carried to the left side under the 

*The condition that permits the discernment of objects at a distance of 10 to 20 
inches beneath the water surface, the method of registration employed by the Wash- 
ington (D. C.) aqueduct office. 

F. C. E. 1897 10 



146 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 

arm and there retained by the arm, the tail being bent slightly upward 
with the left hand. When the fish is properly adjusted its head is 
nearly concealed. The fish is held firmly over a moist pan, and with 
a moderate downward pressure of the right hand the eggs will flow 
freely if mature. The strokes are continued until there are signs of 
blood, which usually accompany the last eggs. The fingers should not 
touch the gills of the fish, as laceration of these organs causes a flow of 
blood injurious to the eggs. Two fish may be stripped into each pan. 

As soon as the spawn is all obtained, the shad is discarded, it being 
impossible to preserve the life of such a delicate fish, even with the 
utmost care. But though it has slight tenacity of life when taken from 
the water, the shad is a very muscular fish, and if not firmly held it will 
flounder and splash in the pan of eggs and probably throw a large 
proportion out and damage some of those that remain. 

The first half teaspoonfu> of eggs should be pressed out into the 
palm of the left hand and inspected. Skilled operatives can usually 
discern ripeness by general outward appearance. A slow and yet 
almost positive test consists in running some of the eggs into water, 
when, if dead, they will have the appearance of boiled rice. But bad 
eggs are sometimes beyond the detection of the most skilled fish- 
culturists. If the eggs are white, opaque, or of milky appearance, the 
fish is put aside. Immature eggs are white, small, and adhering in 
clots; or they may be transparent and yet unyielding to pressure. 
The former are valueless, while the latter can sometimes be utilized by 
putting the fish aside to soften. Both ripe and green eggs sometimes 
occur in the same fish, but only expert operatives can hope to take the 
one and leave the other. If eggs are mature, but little pressure is 
necessary to start them, and if not, they are only injured by squeezing, 
and will either not flow at all, or will come away with difficulty in clotted 
masses and generally with a little blood. After the spawn is taken 
away, the fish has a soft and flaccid appearance about the abdomen, 
which after natural spawning becomes contracted and drawn up, taper- 
ing slenderly toward the tail. 

Eggs of the best grade may be impaired by intermixture of overripe 
or green ones, lumps of milt, tissues of the sperm sac, or fish scales. The 
overripe and unfertilized ones can be discarded, and a tiny net, an inch 
square, or a straw or twig, may be used in removing foreign substances. 
The spawn-taker should clean the eggs before delivering them at the 
hatchery, and no subsequent care can compensate for his neglect. 
Experienced men rarely bring in bad eggs, unless as a result of vari- 
able and unfavorable weather conditions. 

To obtain the milt the spawn-taker catches the fish by the back, 
takiDg hold of the under side with the right hand. Without relaxing 
pressure at any point the milt is forced out with the thumb and fore- 
finger. Good milt is so thin that it flows in a steady stream, and from 
some fish it can be ejected widely over the surface of the eggs, but in 



MANUAL OF FISH-CULTURE. 147 

fish which have been dead some minutes the milt is lumpy and flows 
only in drops. A teaspoonful will fertilize 40,000 to 75,000. After the 
milt has been applied, from half a pint to a pint of water from the river 
is added and the pan given a slow rotary motion, continued till the milt 
is thoroughly mixed, when a milky appearance is imparted to the water. 
When the river water is turbid, clear water must be obtained before work 
is commenced. 

In gill-net boats eggs thus treated will expand without further imme- 
diate attention, for there is sufficient motion from the boat to prevent 
clotting ; shad eggs do not "cement" when the milt is applied to them, 
as in the case with salmon and trout eggs ; but they adhere, and if left 
perfectly quiet, as on shore, a large proportion will be lifeless. Those 
comprising the lower strata may either lack sufficient expansive power 
to absorb water under weight of the others, or in the suction of each 
separate egg 7 in the natural tendency to absorb water, they may have 
a cupping effect upon one another, thus preventing water contact. 
Whatever the cause, they stick together in one mass, and only those 
of the upper layers receive sufficient water; the others remain under- 
sized and die. Large quantities of eggs must be separated, either by 
agitating the water already in the pan or by the addition of more. 

In one minute after thorough mixing the milt can be washed off with 
safety, but usually several pans are to be looked after, when the milt 
may be allowed to remain 5, 10, or even 15 minutes. After the last 
pan of eggs has been fertilized, they are rinsed, beginning with those 
first taken, by pouring in a quart of water, placing the edge of the 
dipper so that the stream is directed between the eggs and the sides 
of the pan, as the eggs may be injured if the water is poured directly 
upon them. Then the pan is oscillated, the water being drained over 
the edge slowly, and, the operation being repeated, the third quart of 
water is left upon the eggs. The eggs must be well stirred with the 
inflowing water. 

There need be no fear of applying too much milt. The amount 
obtained from one fish may be ample for the eggs from two, but it is 
always better to employ two males. Eggs may look promising for two 
or three hours, yet never expand to full size or produce fish. They lie 
at the bottom, and underneath any good ones which may be in the 
pan; they stick to the fingers, while the good ones will not, nor can 
they be successfully removed from hatching-jars until after several 
days' decomposition. By using two pans, good eggs may be separated 
from bad by pouring, but the process is slow and there is usually no 
time in the hatcheries for such operations. 

Good eggs are very transparent and so soft and light that they are 
not apparent to the touch when the fingers are moved among them. 
When the temperature is about 70°, no change is observed for about 
12 or 13 minutes after the milt is added, but about this time a careful 
movement of the fingers in the pan discloses their presence, and in a 



148' RfiK)KT of commissioner of fish and fisheries. 

little more than 20 minutes from the time the milt is applied they feel 
like shot against the fingers, and to an experienced eye are observed 
to increase slightly in size; when a day old, they will not break if 
dropped to the floor. In transferring to other vessels, the rim of the 
smaller pan should be gently immersed beneath the water surface in the 
larger one, and the pouring take place gradually. To prevent splashing, 
in boats, a small pan should be put on the water surface of the larger 
pan. Sudden jars must be avoided, all foreign substances excluded, and 
the pans be free from grease and salt. After the application of milt 
they expand to full size in 20 to 60 minutes, depending partly on tem- 
perature, and at this stage they may be doubled up in the larger pans, the 
question of safety in moving them being determined by their hardness. 




Pans xised in cleaning eggs. 

When eggs are received at the station, in order to thoroughly remove 
all impurities they are passed through netting, and for this purpose, 
two 18-inch flared tin pans with handles, one pan fitting within the 
other, are employed; 2 inches of tne bottom part of the inner pan are 
evenly cut off and replaced with quarter-inch (bar) twine netting. The 
lower pan is filled with water to a point just above the netting, and 
then several quarts of eggs are gently poured in, when they drop through 
the meshes, leaving the fish scales, etc., behind. Thus they are also 
given a change of water, which should be clean and fresh and of about 
the same temperature as that in the hatchery and river. 

If the eggs have absorbed sufficient water in the spawn-pan, they 
swell and adhere to each other, formiug a compact mass, and are ready 
to be transferred to the hatching-jars, but if they are not sufficiently 
expanded or ci water-hardened," they must remain in the pans, from 30 
to 60 minutes being required for their full expansion. 



MANUAL OF FISH-CULTURE. 



149 



HATCHERIES AND EQUIPMENT. 

The building for a shad-hatchery maybe of a temporary character, as 
it is used only about two months each year, but ample light, space, 
ventilation, and arrangements for moderate heating are necessary. The 
steam boiler and pumps should be in a separate structure. 

In exceptional cases, as at Central Station, in Washington, river 
water from city pipes can be utilized. If the water supply is taken 
directly from the river the suction should be put below low-water mark, 
and the end provided with a strainer and kept off the bottom to avoid 
sediment. The water should be supplied from an open tank, not by a 
force-pump, but if it is taken from municipal pipes a regulator may be 
employed. A fall of 16 feet is desirable, or 8 pounds pressure per square 
inch at the top of the hatching-jars. The amount required is 2 quarts 
per minute to each jar. 



Ql 




T] 


! ! 
j i 


| ! 1 INCH FALL V 


|| 




(g) 


j j 

Lli 


J 

i 

i 


S3 



^ reet 



Upper figure showing view froni 
above. 

Lower left-hand figure : End view 
showing hatching-jar in position. 

Lower right-hanrl figure: Cross- 
section showing the drain-pipe and 
trough jn center of table. 




Section A-B 




Shad-hatching: table. 



The jars are arranged on tables, as shown in the cut. From a large 
iron pipe, branch piping of 1£ to 2 inches diameter is run over each 
table, where J-inch brass pet-cocks are inserted 6 inches apart. The 
jars are connected with the supply-pipes by half inch rubber tubing. 
Tight drains are required to carry away the waste water. Collector- 
tanks for fry are rectangular and may be of glass or wood, the former 
possibly preferred. 



150 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 

The overflow from the collectors is guarded by a wire-gauze or cheese- 
cloth strainer. A safe and interchangeable device consists of a stout 
wire frame, over which a cheese-cloth bag is drawn and tied. A 
3 -inch rubber hose is attached to the opening m the frame. The 
strainer is put inside among the fry, and the outflow m an overflow cup. 
The overflow cup is set at the proper height to control the water level 
in the collector-tank. Long-handled nets of ^-inch mesh are required 
to remove egg lumps or other matter from the jars. 

THE AUTOMATIC HATCHING-JAR. 

The United States Fish Commission, in the development of its 
work, had presented to it the necessity of dealing with the eggs of the 

whitefish and the shad upon a 
scale unprecedented in the his- 
tory of fish-culture. Millions 
were to be handled instead of 
thousands, and the removal of 
dead eggs by hand picking was 
no longer to be considered. 
After successive experiments 
the McDonald automatic hatch- 
ing-jar was devised, and it is 
now generally employed. 

The most meritorious feature 
of this apparatus is that it 
prevents the development of 
the saprolegnious fungus, which 
caused so great a mortality in 
some other forms of hatching 
contrivances in which all the ova 
were not in continual movement. 
The very gradual, gentle, and 
continual rolling movement of 
the ova upon each other in the 
jar apparently prevents the 
Automatic shad-hatching jar. spores of the fungus from ad- 

hering The cleanliness of the apparatus is also advantageous, and as 
the material of which it is made is glass, the progress of development 
can be watched satisfactorily from the outside of the jar with a hand 
glass or pocket lens of moderate power. 

The jar consists of a cylindrical glass vessel, of 7 quarts' capacity, 
with hemispherical bottom, supported upon three glass legs. The top 
is made with threads to receive a screw-cap. It is closed by a metallic 
disk, perforated with two holes five-eighths inch in diameter-one in 
the center admits the glass tube that introduces the water into the 
jar, the other, equally distant from the central hole and the edge of 




Report U. S. R C. 1897. (To face page 151.) 



Plate 41 . 




MANUAL OF FISH-CULTURE. 



151 



the metal plate, admits the glass tube which carries off the waste 
water. The central tube is connected by half-inch rubber tubing with 
the pet-cock, which regulates the supply of water. A groove in the 
inner surface of the metallic plate carries a rubber collar, and when 
the plate is in place the tightening of the metallic screw-cap seals the 
opening hermetically. Both the inlet and outlet tubes pass through 
stuffing-boxes provided with gum-washers and binding-screws. The 
central or feed tube is provided with stuffing-boxes, one on the top of 
the disk and one on the bottom, the better to hold it to a true center. 
The outlet tube is provided with only one stuffing-box, and the binding- 
ring is beveled. 

In preparing the jar for work the side tube is fitted first. The glass 
tube should be wet, the gum-washer slipped on the tube about an inch 
from the end and introduced into the opeuing. Holding the tube per- 
pendicularly to the face of the plate, press fairly on the tube, and the 
washer, rolling on itself, will fall into the seat provided for it. Screw 
on the binding- 
ring, and test by 
seeing that the 
tube slides freely 
back and forth in 
tbe stuffing-box; 
if not, it should 
be refitted with a 
heavier or lighter 
washer, as maybe 
required. Glass 
tubes can not be 
procured of abso- 
lute uniformity in Egg Funnel, 
size. Water is the only lubricant that should be used about the jar 
fittings. 

The jar, after being washed clean, is filled with fresh water. A 
shallow tin funnel with a perforated rim is inserted, so that the water 
will stand as high in the funnel-throat as possible, and the eggs are 
poured in by dipperfuls, or when taken from transportation trays are 
washed in by a jet of water. Care is used to have the eggs fall but a 
short distance, and no fish scales or other foreign matter should enter 
the jar with them, as the presence of anything but water and eggs ren- 
ders a proper motion of the mass impossible, and usually results in the 
loss of a large proportion of the eggs. The requisite number of eggs, 
80,000 to 100,000, being in the jar, it is put in position and closed, 
care being taken that both the inlet and outlet tubes slide freely in 
their stuffing-boxes. If the tubes become gummed, let water trickle 
down around the binding-screws. To close the jar, turn on the water, 
place the feed-tube in the jar, turning off the water immediately after 
the feed-tube has passed beneath the surface of the water in the jar, 




152 REPORT OF COMMISSIONER OP FISH AND FISHERIES. 

thus expelling all the air from the feed-tube ; otherwise it would rise 
in bubbles, throwing a portion of the eggs out through the outlet-tube. 

With a proper quantity of semi-buoyant eggs in the jar and the 
water turned on and regulated, the movement of the current estab- 
lishes a regular boiling motion in the mass of eggs, which brings each 
m succession to the surface. This motion may be regulated without 
altering the quantity of water. By loosening the upper binding-screw 
of the central stuffing-box, and pushing the feed-tube down until it 
almost comes in contact with the bottom of the jar, the motion of the 
eggs is increased. If the jar is working properly, the dead eggs when 
brought to the surface remain on top, forming a distinct layer, and by 
pushing down the outlet tube a suitable distance they are lifted up 
by the escaping current and taken out. 

When the water is turned on for the first time the jar should be 
watched closely until a regular motion has been established. When 
eggs have stood 15 or 20 minutes in the jar before the water is turned 
on they do not readily yield to the boiling motion, but tend to rise in a 
solid mass to the top of the jar. By quickly starting and stopping the 
current the mass is readily disintegrated. The degree or intensity of 
motion of the eggs varies not only with their age and condition, but also 
with the condition of the water. If the water is muddy, the motion 
should be rapid enough to prevent mud settling either on the eggs or in 
the bottom of the jar. Ordinarily the best motion is that which readily 
brings the dead eggs to the surface. After the hatching has progressed 
far enough to dispose of a portion of the eggs there is less resistance to 
the current, and it should be reduced by shutting off part of the supply 
or by slightly lifting the central tube. If the motion is not reduced 
from time to time as the hatching progresses, shells will be carried over 
into the receiving-tank with the fish and, being very light, will be drawn 
against the outlet screen, causing an overflow. The motion should be 
so gentle at the time of the greatest hatching as barely to induce the fish 
to swim out of the jar and leave their cast-off shells behind. 

Very healthy eggs, exposed to bright direct sunshine, hatch so rapidly 
that the combined effort of the swarming mass of young fish will 
establish sufficient current to draw some shells over into the receiving- 
tank. This may be modified by placing a screen between the jar and 
the light. The shells under normal conditions remain and form a 
cloud-like layer above the mass of working eggs. As they accumulate 
they should be removed by shoving down the outlet tube until they are 
drawn up with the escaping water. A good plan is to draw several 
jars in succession into a large pan, whence any fish coming over with 
the shells may be ladled into the receiving- tank. 

A remnant of eggs may be long in hatching, and they should be 
poured into a large, clean, bright pan and exposed to bright sunlight, 
when they will hatch in five or ten minutes. 

If the connection of the jar must be broken, it is essential that the 
rubber feed-tube does not drop down and siphon the eggs from the jar. 



MANUAL OF FISH-CULTURE. 153 

In reconnecting, the air may be expelled with the metal top screwed 
down in position. To effect this, draw both glass tubes up to the top of 
the jar and turn on a full head of water, when the air will be forced out 
in bubbles above the eggs, the bubbles escaping through the outlet 
tube. The central tube is now restored to its former position. The 
automatic action permits entire separation of bad from good eggs, 
though some days may be required to accomplish tlie full result. The 
dead become lighter from gases arising from decomposition. A net, 
small enough to easily enter the mouth of the jar and fixed to a handle 
several inches longer than the jar, is convenient for removing particles 
of foreign matter. 

Shad eggs are semi-buoyant, and those which will not rise commence 
lumping on the third or fourth day. The usual period of hatching is 
from 6 to 10 days, sometimes longer, according to temperature of water, 
but with high temperature they will hatch in 3 days. Fry hatched in 
less than 5 days are usually, though not always, weak. In general, the 
period of incubation varies inversely with the prevailing temperature, 
but continuous dark and cloudy days will retard and strong light will 
accelerate development under precisely the same conditions of water 
temperature, and other circumstances not well understood may also 
have their influence. 

Fry when hatched are about 0.37 inch long. They have been meas- 
ured at intervals of from 5 to 15 days, from late in May to the middle 
of October. Toward the middle of August the rate in growth dimin- 
ishes. When 9 days old they are about 0.62 inch long. Fry 0.5 inch 
long July 20th were 0.75 inch long 8 days later; on August 14th, 2 to 
2.25 inches; September 20th, 3 to 4 inches; October 1st, 4 to 4J inches; 
November 4th, 5 to 7 inches. Some years they grow faster than others, 
and in some streams more rapidly than in others. From the State fish- 
ponds at Ealeigh, North Carolina, 33 were removed in November, 1884, 
which measured 8 to 9 inches. Their usual size in the Potomac in the 
fall is 3 to 4 inches. 

MEASURING- THE EGGS AND FRY. 

To estimate the number of eggs and of the young fry was for years 
rather a difficult matter to accomplish satisfactorily. The standard 
made use of at the outset was undoubtedly much too high. The scale 
most used at present is a light square, made of wood, the longer leg 
being 15 inches and the shorter 7£ inches long. The material is £ inch 
wide and J inch thick. The graduations are on the longer leg, and 
read from the lower end upward. The first line is at a height corre- 
sponding to the level attained in the jar by a measured half- pint of 
water, and the succeeding lines are determined by the introduction of 
additional half-pints of water. When the scale is being constructed, 
the central glass tube is stopped at the lower end that it may displace 
an amount of water equal to the amount of eggs it will displace in 



154 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 



practice. Each line on the measuring stick registers 7,000 shad eggs. 
The number of eggs in a liquid pint is established by actual count. 
Those which are very young or have been lately on trays are not of 
normal size and not qualified for measurement. The eggs are at rest 
when measured. 

The jar contents are determined by placing the short leg of the 
measuring-stick over the top, with the other pointing downward and 
touching the side of the jar. The number is indicated on the scale at 
the point opposite the surface of the bulk of the eggs. Scarcely any 
semi-buoyant eggs die, under proper conditions, after hatching out has 
commenced, and a close approximation to the number of fry may be 
obtained from the last measurement, which is 
made after the careful removal of all dead eggs 
and the bursting forth of the first young. 

FEEDING AND REARING. 

The young shad swims vigorously, by rapid 
and continuous vibration of the tail, from the 
moment it leaves the egg. It is colorless, trans- 
parent, and gelatinous. Several hundred in a 
dipper are scarcely discernible. It has a rela- 
tively large yolk-sac, but supports it with ease 
during the first four or five days after hatching, 
the small quantity remaining after this time not 
being visible externally, although found in shad 
fry 14 to 16 days old. Minute conical teeth make 
their appearance on the lower jaws and in the 
pharynx about the second or third day after 
hatching. The jaws at three months are armed 
with teeth slightly curved. 

Young shad feed on other minute organisms, 
such as exceedingly small crustaceans. Food 
has never been observed in the alimentary canal 
until ten or twelve days after the young fish had 
left the egg. At about the middle of the second 
Application of a measur- week considerable may be seen, but the intestine 
ingscaletoa jar of shad i s then not often very densely packed. At the 
e SS s - age of three weeks an abundance of food is 

found. They have been known at this early age to eat their own kind, 
and later the young carp and salmon. When cold, raw winds drive 
the crustaceans into deeper water, the young shad follow them, and 
in aquaria they take Crustacea freely. In salt-water aquaria they may 
be fed upon chopped oysters and canned herring-roe. 

Experiments with young shad have been carried on for several years 
at Central Station in salt-water aquaria. On one occasion about 250 
were received in October, at which time they were about five months 
old. They were put in brackish water, specific gravity 1.005, which 




MANUAL OF EISH-CULTURE. 155 

was added to from day to day for nearly a week, when it was brought 
up to 1.018, or the same specific gravity as the water used in the marine 
aquaria. At the time these were placed in the brackish water others 
were put into fresh-water aquaria, but the latter died within three 
days. Those in salt water began in two or three days to take food, 
consisting of chopped oysters, clams, and beef, the preference being 
for oysters. At first they would take food only when it was sinking, 
later they began taking it off plants where it had lodged, and finally 
from the bottom. Nearly all remained healthy, plump, and active for 
six months, some living until about midsummer. 

For ten years past two or three million shad fry have been reared 
annually at the Fish Ponds, Washington, D. C. A 6-acre pond is used, 
the water supply being taken from the city water-works. The depth 
varies from 2 to 3 feet, and throughout the whole extent there is a dense 
growth of water-plants, among which crustacean food multiplies — new 
supplies being brought in from the water-pipes. Fingerling shad are 
so tender that the numbers annually liberated can not be ascertained ; 
they can not withstand the handling consequent upon counting them, 
not even undergoing transfer in dippers of water, and their scales drop 
off on being touched ; consequently at high tide they are liberated into 
the Potomac through a sluice-gate with an outlet pipe about 2 feet in 
diameter. They require some days to make their escape. By conserva- 
tive estimate 50 to 60 per cent are held safely until about October. 

Rearing has been experimentally tested at Wytheville and Neosho 
with good results. At Neosho on the 3d of June, 1892, 700,000 fry were 
received from Gloucester, N. J.; their growth was satisfactory. In 
preparing for their release the hatchery branch was cleared of shoals, 
drifts, and aquatic plants for three-quarters of a mile, and early in 
November, when the branch was swollen with rain water, 200,000 
G-months-old fish were allowed to pass through open gates; they were 
some hours in escaping, in a continuous silvery mass. These were the 
first fingerling shad planted in waters tributary to the Gulf of Mexico. 

TRANSPORTATION. 

Good, healthy fry will pass from the jar to the collector -tank as fast 
as hatched, and unless too thick will not lie on the bottom of the tank, 
although they sometimes crowd on the side nearest the strongest rays 
of light. As many as 500,000 to 800,000 are collected in each tank. 
In transporting, they must be kept in vessels with smooth surfaces, 
preferably tin-lined cans. Zinc vessels are destructive, and galvanized 
cans are not recommended. 

About 2,000 to 3,000 fry are put to a gallon of water, which must be 
pure enough for ordinary drinking purposes and well aerated. The 
water in the cans must be kept at 58° to 65°, though in rivers and 
ponds the fry endure a temperature of 90° F. 

As early as 1874, experiments were carried on to retard the develop 
ment of eggs, in order to provide a longer period between the delivery 



156 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 

of the eggs from the parent fish and the absorption of the yolk-sac. 
Eggs, when transported, were placed on trays and put under melting 
ice, and later experiments have been conducted inside refrigerator 
boxes. Pathological changes or deformities are induced in the embryos 
when subjected to too low a temperature or when held long enough on 
damp flannel trays (ordinary air temperatures) to hatch. 

It would appear that 55° to 53° is the lowest temperature in which 
ova will safely undergo their normal development and 9 days is the 
longest period of incubation attainable at that temperature — time suffi- 
cient, when added to the several days required for the young to absorb 
the yolk-sac, to ship them to Europe, which has so far failed. One 
drawback is the rapid development of fungus, which grows over the 
eggs, penetrates the membranes, and kills the ova. 

Retardation of the hatching of shad eggs has not been turned to 
practical account, but eggs can be transported hundreds of miles on 
trays, large numbers being moved at a relatively small expense com- 
pared with the same number of fry. 

Eggs from the Potomac River are sent to Washington, a distance of 
12 miles, by steamer, and nearly a mile over cobblestone streets in 
Washington. Formerly they were put on the trays soon after being 
taken, but in April, with night air-temperature as low as 49°, and in 
June, with the relatively high temperature, the quality was bad ; they 
did well between 60° and 65°, and later they were put into hatching- 
vessels and kept in motion 12 hours, when they became hard, and went 
forward in better condition. Since 1888 they have been retained in 
hatching-jars for 36 hours preceding transfer. 

They are shipped in crates of 20 shallow trays, the frames of the 
latter being of wood with bottoms of wire mesh about 8 to the linear 
inch. Wood and wire are painted with asphaltum. Each tray is 
covered with cheese-cloth, somewhat overlapping the edges, the cloths 
being hemmed, to avoid ravelings. There are two frames of wood, 
connected with leather straps; one the base and the other the cover for 
the stack of trays. The trays, after being' filled with eggs, are wrapped 
in a long, cotton-goods apron and strapped together. There is an iron 
handle on the top frame, and the lowermost tray is put down empty 
with the wire surface upward. Then follow the trays containing eggs, 
the uppermost one being put on empty with the wire surface up. The 
top and bottom trays are merely to protect the others. 

The greater part of the water above the eggs is poured off from the 
jars and the remainder poured into tin pans along with the eggs. 
The cloths, after soaking in water, are arranged one by one on the 
trays and tucked closely into the four corners. The trays are stacked 
up and eggs poured evenly over the surface of the top one with a 
large dipper, and each tray, when filled, is put on the crate base. The 
surplus water drains away to the manipulating table. Tray cloths of 
material too closely woven to let the water through are unsuitable. 
The eggs are bailed up in dippers with the water that they are in, and 



MANUAL OF FISH-CULTURE. . 157 

usually spread two layers deep, but can be put ou more thickly. When 
eighteen trays are filled they are wrapped in the outer cloth, previously 
soaked in water, and tightly buckled together. The crate covers and 
tray cloths are boiled in water each time after use. 

Each tray — 14 by 19 inches area, with two layers of eggs — holds 
about 20,000 eggs, the contents of a full crate representing from 300,000 
to 400,000 eggs. While in transit the crates are sprinkled with river 
water on the sides at least once an hour, and kept in the shade, away 
from the cooling influence of the wind, to preserve even temperature. 

TRANSPLANTING. 

The propagation of shad is mainly carried on to maintain or increase 
the supply in rivers where the species is native, and the fry are liber- 
ated with that end in view; but the shad has also been planted, in 
some cases with great success, in waters in which it was either unknown 
or found in small quantities. Large numbers of fry have been liberated 
in - tributaries of the Gulf of Mexico, but without marked results. 
Between 1873 and 1892 several million fry were experimentally placed 
in the waters of Great Salt Lake, Utah Lake, and Bear Lake, Utah. 

From 1884 to 1886, 3,000,000 fry were liberated in the Colorado Eiver 
at the Needles, in Arizona. It was believed that the shad would be per- 
manently confined to the Gulf of California by the warm water of the 
lower part, and would then return to the Colorado and Gila rivers to 
spawn. The time having gone by when the adults should return, the 
experiment is regarded as without result. It has been found that the 
shallow waters at the mouth of the Colorado Biver are barren of life 
and the conditions are unfavorable to stocking that river with shad. 

Bernarkable success attended the stocking of waters of the Pacific 
Coast northward from Monterey. In 1871, 12,000 shad fry from the 
Hudson Biver were liberated in the Sacramento Biver by the California 
Fish Commission, and in 1873 the United States Fish Commission made 
a second deposit of 35,000. Subsequent plants in the Sacramento, 
aggregating 609,000, were made by the United States Commission from 
1876 to 1880. From these small colonies, amounting to less than 1 per 
cent of the number now annually planted in the Atlantic Slope rivers, 
the shad have multiplied and distributed themselves along nearly 3,000 
miles of coast from southern California to southeastern Alaska. 

The shad rapidly made their way up the coast from San Francisco 
Bay. They reached Bogue Biver, Oregon, in 1882. In the Columbia 
a few were taken as early as 1876 or 1877. About 1881 or 1882 they 
were on the coast of Washington, reaching Puget Sound in 1882. They 
appeared in the Fraser Biver, British Columbia, in 1891 ; and in the 
Stikine Biver, near Wrangell Island, Alaska — latitude 56° 30' — the 
same year. The species now is found along the entire coast from Los 
Angeles County, California, to Chilkat, Alaska, covering 22 degrees of 
latitude. Its distribution, considered from the standpoint of commer- 
cial importance, is from Monterey Bay to Puget Sound. 



158 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 

On the northern part of the coast the first fry were introduced in 
1885, the number being 60,000. Of these, 50,000 were put in the Willa- 
mette River and 10,000 in the Snake River. In the following year 
850,000 were introduced into the Columbia River, making a total of 
910,000. 

The increase has been uninterrupted and rapid in California waters, 
and the shad is now one of the most abundant fishes of that State. 
As a result of the liberation of the first two consignments, consisting 
of 45,000 fry, several thousand mature shad were caught in 1879, and 
sold in the San Francisco market. In 1880 specimens of all sizes were 
taken in the Sacramento River and Monterey Bay, and it was evident 
that the shad had begun to multiply. Up to 1883 the increase was 
marvelous. Prohibitory law did not prevent their incidental capture 
in salmon nets, their abundance being thus indicated. 

The shad is most numerous on the west coast in San Francisco Bay 
and its tributaries. It is not common above Sacramento, owing to the 
low water-temperature. In the Columbia it is regularly found as far as 
the Cascades, about 150 miles above the mouth of the river. Contrary 
to their habit in eastern rivers, shad are found in the rivers tributary 
to San Francisco Bay and the coastal waters of that vicinity throughout 
the year. 



Report U. S. F. C. 1897. (To face page 158.) 



Plate 42. 




BATTERY STATION HATCHERY. HAVRE DE GRACE, MARYLAND. 




U. S. FISH COMMISSION CAR LOADING AT NEOSHO, MISSOURI. 



Report U. S. F. C. 1897. (To face page 159.) 



Plate 43. 




Report U. S. F. C. 1897. (To face page 159.) 



Plate 44. 




THE BUCK BASSES, CRAPPIES, AND ROCK BASS. 



DESCRIPTION OF THE FISHES, COMMON NAMES, ETC. 

The species treated of in this chapter are those members of the 
Centrarchidae (or fresh-water simfishes) which have come under the 
scope of fish- culture, namely, the large-mouth black bass (Blicropterus 
salmoides), the small-mouth black bass (Micropterus dolomieu), the rock 
bass (Ambloplites rupestris), the crappie (Pomoxis annularis), and the 
calico bass (Poxomis sparoides). Whatever is said of the rock bass will 
apply equally well to other sunfishes, which might be here considered 
but which have not been artificially reared. 

The principal physical characters of these fishes are indicated in the 
following key, which serves to distinguish the two species of black bass 
and the two species of crappie from each other as well as from less 
closely related species. 

Large-mouth black bass : Body comparatively long, the depth about 
one-third the length; back little elevated; head large, 3 to 3£ in body; 
eye 5 to 6 in head; mouth very large, the maxillary in adults extending 
beyond eye, smaller in young. Ten rows of scales on the cheeks; body 
scales large, about 68 in the lateral line, and 7 above and 16 below the 
line. Dorsal fin low, deeply notched, larger than anal, with 10 spines and 
12 or 13 soft rays; anal with 3 spines and 10 or 11 rays. Color above 
dark- green, sides greenish- silvery, belly white; young with a blackish 
band along sides from opercle to tail, the band breaking up and growing 
paler with age; caudal fin pale at base, white on edge and black between; 
older specimens almost uniformly dull greenish; three dark oblique 
stripes across opercle and cheek; dark blotch on opercle. 

Small-mouth black bass : Similar in form to large-mouth bass. Mouth 
smaller, the maxillary terminating in front of posterior edge of eye, 
except in very old specimens. About 17 rows of small scales on the 
cheeks; body scales small, 11-74-17. Dorsal fin less deeply notched 
than in other species, with 10 spines and 13 to 15 rays; anal with 3 
spines and 12 or 13 rays. General color dull golden-green, belly white; 
young with dark spots along sides teuding to form irregular vertical 
bars, but never a lateral band ; caudal fin yellowish at base, white at 
tip, with dark intervening area ; dorsal with bronze spots and dusky 
edge; three radiating bronze stripes extending backward from eye; 
dusky spot on point of opercle. 

Crappie ; Body short, greatly compressed, back much elevated ; depth 

159 



160 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 

2£ in length; eye large, one- fourth length of head; head long, 3 in 
length; profile with double curve; mouth large, snout projecting. 
Scales on cheeks in 4 or 5 rows; scales in lateral line 3G to 48. Dorsal 
fin smaller than anal, with 6 spines and 15 rays, the spinous part the 
shorter; anal with 6 spines and 18 rays; dorsal and anal fins very 
high. Color silvery white or olive, with mottlings of dark green ; the 
markings mostly on upper part of body and tending to form narrow, 
irregular vertical bars; dorsal and caudal fins with dark markings; 
anal nearly xdain. 

Calico bass : Similar in form to crappie, but the body shorter, back 
more elevated, and profile of head straighter; depth, one-half length; 
head one-third length; mouth smaller than in crappie; snout less pro- 
jecting. Six rows of scales on cheeks, and 40 to 45 along lateral line. 
Dorsal and anal fins higher than in crappie ; dorsal spines 7 or 8, rays 15 ; 
anal spines 6, rays 17 or 18. Color, light silvery- green, with dark-green 
irregular mottlings over entire body; dorsal, caudal, and anal fins with 
dark-olive reticulations surrounding pale areas; whole body sometimes 
with a delicate pink reflection (whence the name strawberry bass). 

Rock bass : Body oblong, compressed, back moderately elevated; 
depth 2 to 2£ in length; head large, 2| in length; eye very large, 3^ 
in head. Scales 5-39-12, in 6 to 8 rows on cheeks. Dorsal fin much 
larger than anal, with 11 spines and 10 rays; anal, with 6 spines and 
10 rays. Opercle ending in two flat points; gillrakers less than 10. 
Color olive-green, with brassy reflections; young irregularly barred 
and blotched with black ; adult with a dark spot at base of each scale, 
forming interrupted and inconspicuous stripes ; a black spot on opercle; 
anal, caudal, and soft dorsal fins with dark mottlings. 

The most reliable character for distinguishing the large-mouth from 
the small-mouth bass is the number of rows of scales on the cheeks. 
The colors of each species vary with age and the size of the mouth 
varies with the size of the fish, but the scales are constant under all 
conditions. With the crappies, the leading differential feature is the 
number of dorsal spines. 

By reason of their wide geographical range, the black basses have 
received a multiplicity of popular names. The large-mouth black bass 
is known as Oswego bass, lake bass, green bass, yellow bass, moss 
bass, bayou bass, trout, jumper, chub, and welchman. In the North it 
is generally called black bass; in Virginia and North Carolina it is 
usually designated as the chub, and in Florida and the Southern States 
it is often called trout. The small-mouth black bass has received the 
common names of lake bass, brown bass, ninny bass, hog bass, black 
perch (used in the mountain sections of Yirginia, Tennessee, and North 
Carolina} trout perch, brown trout, jumper, mountain trout, together 
with other names of purely local use. 

Rock bass are variously known as red-eye, red-eye perch, arTd goggle- 
eye, and are sometimes confounded with the warmouth (Ghcenobryttus 
gulosus), which bears some of the same common names. 



MANUAL OP FISH-CULTURE. 161 

The calico bass has received the names of strawberry bass, grass bass, 
bitter-head, barfish, lamplighter, goggle-eye, goggle eye perch, speckled 
perch, and speckled trout. The crappie is known in its native waters 
ascrappie, new light, campbellite, sac-a-lait, bachelor, chinquapin perch, 
croppie, and cropet. On account of the similarity of the calico bass 
and crappie, anglers and fish-culturists have frequently confounded 
the two, the common and local names often being used interchangeably 
throughout the regions to which both are native. 

Possibly no common name of the black bass is more appropriate than 
"jumper," which is applied in certain parts of Kentucky. That both 
species of the black bass are jumpers is well known to every angler, 
but it is better understood by those who have had occasion to collect 
these fishes by seining. It is almost impossible to capture them with a 
seine rigged in the ordinary manner, especially when the fish have the 
vitality and activity which is usual when living in water of moderate 
temperature. Like other fishes, they lose in strength and activity 
when they inhabit warmer waters. While the black bass of the colder 
northern waters make a fight worthy of the salmon, they may be taken 
from the waters of the south with hardly a struggle. In seiniug for 
brood stock it is well to employ a seine about three times the depth of 
the water, as the bagging or bellying of a seine so rigged confuses the 
fish and deters them from jumping. 

On one occasion, when collecting black bass on the Holston Eiver, 
advantage was taken of their jumping habits to effect their capture. 
A flatboat 12 feet wide and 50 feet long was procured and in suitable 
places was rapidly poled broadside from one bank to the other. As it 
approached the further shore the bass would leap from the stream and 
frequently land in the boat, the gunwale of which was cut down to 
within 4 inches of the water. One bass was seen to clear the entire 
width of the boat, making a horizontal jump of 14 feet. 

A marked characteristic of the rock bass is their habit of settling 
down in dense, compact masses, resembling a swarm of bees, which is 
especially true of the young in cold weather. They are exceedingly 
pugnacious, and sometimes seem to take the hook rather on this 
account than from a desire for food. They are well adapted for pond- 
culture, and under proper conditions will repay the culturist in a large 
crop of young with the expenditure of very little labor and time. 

The calico bass is a fairly game fighter, and its firm, white flesh has 
a fine flavor when the fish is taken from cool, pure waters; but it is a 
very delicate fish to artificially propagate. It seems to resent captivity, 
and especially when taken from warm waters is exceedingly tender, 
quick to yield to attacks of fungus, and liable to become blind and die. 
Of large numbers collected and transplanted in new waters many have 
died within a few days after being deposited. 

The spawning and breeding habits of the calico bass and the crappie 
are so nearly like those of the rock bass that special remarks on {he 
subject do not appear necessary. 

F. C. P v . 1897 11 



162 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 
GROWTH AND WEIGHT. 

There is a wide difference in the rate of growth, and there is no way 
by which the age of a black bass can be determined from its size. 
Some are comparatively large from the moment they n,re hatched, and 
grow much more rapidly than the smaller members ot the same school. 
The average size of adults varies in different localities, and sometimes 
will be found to vary from year to year in any particular locality. The 
variations depend upon initial vitality, upon the scarcity or abundance 
of food, and upon the range and space given the fish. At the age of 
5 or 6 months the young bass measure from 4 to 8 inches, according to 
locality and surroundings, though a certain percentage of the crop will 
always run large. In 1892, at Neosho station, a black bass, which was 
positively known to be under 18 months old, weighed on the scales 1 
pound 9 J ounces. 

Large-mouth bass have been known to weigh 23 pounds. They are 
not infrequently taken from the San Marcos Eiver, Texas, weighing 
from 12 to 15 pounds, and a 6-pound or 8-pound bass in the southern 
tributaries of the Mississippi and in the inland lakes of Florida excites 
no surprise. The small-mouth bass does not grow so large, 2£ pounds 
probably exceeding their average size, though they occasionally reach 
5 or 6 pounds. The rock-bass fry grow slowly, those 6 months old 
seldom averaging 2 inches in length. The adult usually weighs from 
£ to f pound, occasionally reaching 1 pound; and examples have been 
recorded as high as 3 pounds. 

The crappie and the strawberry bass will, as a rule, not exceed 1 
pound in weight, though in Missouri the former has been taken as 
high as 3 pounds. Under like conditions of pond environment, at 6 
months old the young of both these species are about the size of black- 
bass fry of the same age, possibly a little smaller. Each school will 
have a few individuals much larger than the majority. 

NATURAL HABITAT AND DISTRIBUTION. 

The large-mouth and small-mouth black basses are widely distrib- 
uted. The natural range of the large-mouth is from the Great Lakes 
and the Eed Eiver of the North to Florida, Texas, and Mexico, and 
west to the Dakotas, Nebraska, and Kansas. The small-mouth bass 
ranged formerly from Lake Ckamplain to Manitoba, and southward on 
both sides of the Alleghanies to South Carolina and Arkansas. The 
adaptability of these fish to extremes of temperature and their great 
tenacity of life under seemingly adverse conditions has rendered their 
distribution comparatively easy, and they have been successfully intro- 
duced into nearly all the sections of the United States to which they 
were not native, and into England, France, Germany, and Finland. 
They have been planted in California, Washington, Utah, and other 
Western States by the United States Fish Commission. In three years 
they became so numerous in Utah that 30,000 pounds were caught and 
marketed from one lake. 



Report U. S. F. C. 1897. (To face page 163.) 



Plate 45. 



' 1 1 ■■ 






• l VII ! il I ' '' 

" ■ • i,'„ ' ; 




; .... 




Report U. S. F. C. 1 897. (To face page 1 63.) 



Plate 46. 




Report U. S. F. C. 1897. (To face page 163.) 



Plate 47. 




MANUAL OP FISH-CULTURE. 163 

Two notable early instances of the successful transplanting of black 
bass in a primitive way may be mentioned, the fish being transferred 
in the tender of a locomotive — once in 1853, when the Potomac was 
stocked, and again in 1875, when, under the direction of the Commis- 
sioner of Fisheries of Virginia, adult black bass were moved from the 
Eoanoke Eiver across the divide to the New Eiver, a tributary of the 
Kanawha. Up to 1875 the Kanawha contained no bass, and its edible 
fishes consisted almost entirely of catfish, but for the past ten or a 
dozen years thousands of bass have been taken from New Eiver and its 
numerous tributaries, draining ten counties of Virginia and running 
through parts of North Carolina and West Virginia. New Eiver was also 
successfully stocked with rock bass by the Virginia Fish Commission, 
the fish being brought from Holston Eiver, a tributary of the Tennessee 
in Washington County, Virginia, in June, 1876, and deposited in the 
smaller tributaries of New Eiver, in Montgomery County, Virginia, 
whence they have colonized the entire New Eiver basin. 

Few fish thrive in water of such varying extremes of temperature as 
the large-mouth black bass, and, to a certain extent, the small-mouth. 
The former are found in water covered with ice and in that standing 
at 100° F. ; but with both species sudden changes of temperature fre- 
quently prove fatal. 

The small-mouth black bass seeks pure, rapid, fairly clear streams, 
and lives at higher elevations and in clearer waters than the large-mouth. 
In the northern part of its range it becomes torpid in winter, but in 
the warmer waters of the South it is active throughout the year. The 
large-mouth black bass also likes pure, clear water, but often inhabits 
the hot and stagnant bayous and ponds of the South. It has been 
seen in great numbers under conditions of high temperature and muddy 
water which would ordinarily be fatal to all forms of aquatic life except 
of a very low order. Many die under these conditions, but numbers 
live for months and some possibly for years. Those from hot, stagnant 
waters, however, have a soft, flabby flesh, and are apt to be infested 
with parasites; they spoil quickly and are not palatable. Bass do not 
voluntarily seek such unfavorable surroundings, and their presence 
there is attributable to accident. The bass found in the Mississippi 
valley under these conditions have been left by the spring freshets, 
and, failing to go out with the slowly receding waters, they reproduce 
in great numbers in the ponds and lakes temporarily formed in the 
depressions of the land. The surroundings are generally either rich 
alluvial meadows or swampy forests, from which the receding water 
drains an infinite quantity of natural food for the sustenance of the fish 
retained in the temporary ponds. 

The rock bass is indigenous to the Great Lakes region and Missis- 
sippi Valley, and there is evidence to show that it is native to certain 
streams on the east side of the Alleghanies. It has been successfully 
introduced into many new waters. In its native waters it is found in 
the winter months under ice, and stands a high summer temperature, 



164 REPOET OF COMMISSIONER OF FISH AND FISHERIES. 

though not so great as the black bass. The highest temperature to 
which it has been subjected at Neosho is S8°. The transportation of 
this species would indicate that it suffers from change of temperature 
as quickly as the black bass, with possibly this difference, that while 
the black bass seems to be more quickly and fatally affected by a change 
from high to low temperature, the opposite change more quickly and 
injuriously affects the rock bass. Though sometimes found in muddy 
bayous and in waters of the middle South stained by decaying vegeta- 
tion, the rock bass thrives better in clear, pure waters well stocked with 
aquatic plants. 

The natural habitat of the calico bass is the Great Lakes region, the 
entire Mississippi Valley south to Louisiana, and the streams of the 
Carolinas and Georgia east of the Alleghanies, while its close kin, the 
crappie, is confined to the Mississippi Valley, though it is sometimes 
taken in the Great Lakes region. The calico bass is said to demand a 
higher temperature and clearer water than the crappie, but this is not 
certain. 

NATURAL FOOD, ETC. 

The natural food of the black basses varies greatly, and is influenced 
by the spawning season, character and temperature of the water, and 
the weather. They are voracious and pugnacious, and devour other 
fish almost indiscriminately. The food of the adults comprises crayfish, 
minnows, frogs, tadpoles, worms, and mussels, and the young feed on 
insects and other minute forms of life found in water. 

At times both the large-mouth and small-mouth bass refuse the 
most tempting bait, and at other times they bite greedily at almost 
everything. Various kinds of animals of a suitable size, even rats and 
snakes, and many varieties of vegetables, have been found in their 
stomachs, and in a wild state under some conditions they devour almost 
anything moving in or immediately over the surface of the water. 

The black basses afford perhaps the highest type among fishes of 
parental care and watchfulness, guarding their young until after the 
dispersal of the school of fry ; but a large part of the young, so zeal- 
ously protected early in the season, at a later date furnish food for 
adult bass, possibly their own progenitors. As with trout, bass of the 
same school of young vary in size, and the larger prey mercilessly upon 
the weaker, often attacking their own kind when other natural food is 
abundant. 

COMMERCIAL IMPORTANCE. 

The market value to the fishermen of the black bass taken in the 
United States amounts to about $130,000 annually, a sum represent- 
ing over 2,000,000 pounds of fish. A great part of the bass caught, 
however, never reach the market, being consumed by anglers and their 
friends. The indirect value of bass fishing to rural districts, in the 
expenditures of visiting sportsmen for boats, guides, teams, supplies, 
and accommodations, is very great. 



MANUAL OF FISH-CULTURE. 165 

Ten years ago it was said that black bass did not exist in sufficiently 
large numbers to ever become a staple article of food, but they now 
furnish important additions to the food supply of many thousands of 
people. The annual sales in New York are estimated to be at least 
50,000 pounds, with an average value of 10 cents per pound. Possibly 
because of the abundance ofwhiteflsh and lake trout, Chicago does 
not seem to afford as good a market for bass as other large cities. A 
recent estimate places the sales of all the bass handled by wholesale 
dealers of Chicago at 15,000 pounds, but these figures are probably too 
low. The Illinois fishermen ship nearly 50 tons of black bass to the 
markets annually, and it is a reasonable assumption that Chicago con- 
sumes a very large part of the production of the surrounding country. 

The States in which the black-bass fishery is most important are 
North Carolina and Ohio; in 1890, over 400,000 pounds, valued at 
$20,500, were caught for market in North Carolina; in Ohio, in 1894, 
nearly 300,000 pounds, worth over $22,000, were taken. Other States 
in which there is an annual yield of over 100,000 pounds are Arkansas, 
Florida, Minnesota, Missouri, and ISIew York, and in about twenty other 
States this fish is of some commercial importance. 

The annual catch of crappie for market, according to recent statis- 
tics of the United States Fish Commission, is about 850,000 pounds, 
having a first value of $39,000. The leading States in this fishery are 
Arkansas, Illinois, Minnesota, Missouri, and Tennessee, the three first 
named producing more than half tbe yearly yield. The market value 
of the rock bass is not large. Crappies are generally considered better 
food-fish than the rock bass and enter much more largely into commerce. 
As with black bass, a very large percentage of the catch of crappies, rock 
bass, and sunfishes does not reach the markets. 

LIMITATIONS OF BASS-CULTURE. 

The artificial propagation of black bass, by taking and impregnating 
the eggs, has not been, up to the present time, practically successful. 
Unlike the shad and salmon, eggs can only be stripped from the female 
with great difficulty, and it has been necessary to kill the male to obtain 
the milt. Another obstacle is the difficulty of finding the two sexes 
ready to yield the eggs and milt at the same time, even when they are 
taken from over the' nests apparently in the act of spawning. Inter- 
ruption or handling seems to prevent the discharge of eggs or milt. 
At Neosho unsuccessful efforts were made daily for several weeks to 
spawn a female black bass in which a part, at least, of the ovaries were 
fully developed. The fish was so near the point of spawning that when 
held head downward the eggs could be seen to roll forward toward 
the head, and when reversed to drop in the opposite direction. 

Since a way to artificially impregnate the eggs of the bass has not 
yet been discovered, and the handling of eggs with indoor apparatus is 
impossible, it is fortunate that the natural impregnation of these fishes 
reaches a percentage closely approximating that which fish-culturists 



166 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 

have been able to secure by artificial means from other species, and also 
that the parental instinct is unusually developed. The first conditions 
make pond-culture necessary and the second render it possible. The 
methods hereafter described are those in use at Neosho station. 

ARTIFICIAL PONDS FOR REARING BASS. 

The size of spawning-ponds is controlled, to a certain extent, by cir- 
cumstances. Small ponds which are long and narrow, with the inlet 




Plan of Neosho Station, showing shape and depth of-ponds, with location of hatchery 
and superintendent's dwelling. 

at one end and the outlet at the otber in the line of the longest axis, 
produce the best results, as the strength of the current can be better 
controlled, and the whole pond regulated under the scrutiny of attend- 



Report U. S. F. C. 1897. (To face page 167.) 



Plate 48. 





MANUAL OP FISH-CULTURE. 167 

ants from the shores. Large ponds furnish wider range, and this is 
desirable when fish are raised for market, but large spawning or 
nursery ponds are not recommended; and if the object is to produce 
large quantities of young for distribution in new waters small ponds 
are undoubtedly better. 

At least one-fourth of the pond should be not over 1 foot in depth, 
and this portion should be planted with pond-weed (Potamogeton) and 
water- weed (Elodea or Anacliaris) to facilitate the production and 
growth of the minute animals, which furnish so large a part of the food 
for the young bass. The remainder of the pond should have a gradually 
sloping bottom, and consequent increase of depth to the kettle (or 
draw-off), where the water must be at least from 3 to 6 feet deep for the 
warm Southern States, and 12 to 14 feet deep for the Northern States, 
to provide against the danger of freezing. In the middle third of the 
pond water-lilies should be planted, preferably those having the largest 
pads, such as the Nymphea alba; these plants not only furnish the 
breeding fish a hiding-place from fish-hawks, but serve as sunshades 
during the summer. It is not usually advisable to place large bowlders 
in the ponds, as they are in the way of seining or netting, and furnish 
an acceptable resort for crayfish. 

When the young, under the guidance of the parent fishes, are school- 
ing, they may be collected from the nests and deposited in waters to 
be stocked, or transferred to nursery-ponds. These ponds should be 
constructed to afford young bass protection from enemies and to produce 
the greatest quantity of insect life suited to their sustenance, and this 
is better accomplished with a number of small ponds than with one 
large one. A good working size is from 40 to 50 feet long by 12 to 15 
feet wide, with a depth of from 30 to 36 inches for the "kettle." 

Where the topography of the ground will permit, it is best to have 
the nurseries immediately adjoining the spawning-pond, with the water 
supply from the same source, so that there will be but slight difference 
between the temperature of the shallowest part of the nursery-pond 
and the surface water of the other. As in all other ponds for fish 
propagation, the supply and discharge for each nursery-pond should 
be independent of any other, and the bottoms be made to slope toward 
the "kettle." The young large-mouth bass is not a strong fish, and 
currents in the spawning and nursery ponds should be avoided for 
some time after the spawning period. 

If the locality is infested with crawfish, it is advisable to pile or 
otherwise protect the banks; and the entrance of snakes, frogs, and 
such enemies may be prevented by surrounding the pond with finely 
woven screens, or, better yet, boards let into the earth a few inches 
and projecting above the ground. The pond should be supplied with 
the aquatic plants previously mentioned as desirable for the shallow 
parts of the spawning-pond. 

A plan has been suggested, which combines the features of a spawn- 
ing and nursery pond, by constructing one comparatively long pond, 



168 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 

narrow near the middle, so that the general shape will be like a dumb- 
bell with a very short handle. Across the narrow part is to be stretched 
a screen of ^-inch wire cloth, which will confine the spawners to the 
deeper end of the pond, while the fry, following their instinct of 
moving upstream, will find their way through the screen into the 
upper, shallower end. This method would apparently not only save 
much labor in transferring the fry, but obviate the risk involved in 
handling tbem. 

If it is desired to hold the bass until they attain their full growth, 
the fry are transferred to troughs or pools where they are reared in a 
purely artificial manner — that is, tamed and trained to take prepared 
food. For this purpose modifications in the shape and arrangement of 
the spawning-pond are necessary, somewhat as described above for the 
combination pond. The shallow part near the inlet has a long, narrow 
neck and the general shape, where the ground permits, follows the 
outline of a gourd. That part which resembles the handle is screened 
off from the remainder with wire netting, with a quarter-inch or less 
mesh. The young fry, after the dispersal of the school, seek the shal- 
low waters, which, warmed by the sun, at this time of year afford rich 
pasture of Cyclops., Daphnia, young Gorixa, and other small invertebrates. 
Following the natural inclination of young fishes to head toward the 
source of the water supply, they pass through the screen and collect 
within the neck of the pond, where the food supply will be found to be 
greater than around the margin. From this part of the pond the fry 
have no inclination to retreat, and the parent fish can not follow and 
devour them. 

TROUGHS. 

The ordinary horizontal trough in general use in trout-culture is well 
adapted to raising young bass fry. A trough 12 to 14 feet long with 4 
inches depth of water at 57°, changing 2 gallons per minute, will sup- 
port from 3,000 to 5,000 black-bass fry, and twice or three times as many 
rock bass will live comfortably under like conditions. For bass of 
larger size, fingerlings and upward, vats or pools answer better than 
troughs. The troughs can be so arranged that the water discharged 
from them furnishes the supply for one or more pools. The shape, size, 
and number of the pools must be regulated by the topography of the 
land, though they should not be wider than 6 feet, nor with a depth of 
water greater than 2 feet, and either lined with plank or built of brick 
or stone. Wire netting or guard-boards, projecting 1 to 1£ feet above 
the ground, prevent the entrance of snakes and other enemies. As 
with all ponds, provision is made to entirely empty one pool without 
interfering with the water supply of another, and to have a good fall 
from inlet to outlet. The length of the pool must be regulated by the 
lay of the land, and, if long, it is advantageous to divide the pool into 
sections, with movable screens of wire cloth for convenience in handling 
several sizes of fish. 



MANUAL OF FISH-CULTURE. 169 

The same general care and cleaning usually given to troughs con- 
taining trout fry is necessary in cultivating bass. The trough is swept 
down twice a day and occasionally washed inside with a cloth, and the 
water supply, conduits, and outlets frequently examined and kept clear 
and clean. 

The young bass is able to stand any temperature to which the sun 
raises the water of the nursery ; those hatched in water at 56° F. will 
thrive two months later with the temperature at 86°. However, bass 
grown in very high temperature are exceedingly tender, and can not 
be handled and transported until the approach of fall and winter has 
gradually reduced the temperature and so hardened them. Moreover, 
under such conditions they are more liable to attacks of parasites, both 
external and internal. While bass can live in water ranging from 33° 
to 98°, more moderate limits are desirable. The Cyclops and some 
other of the natural forms of food for young bass reproduce best at a 
temperature between G8° and 70°, and can not resist higher than 95°. 

CARE OF PONDS. 

It is desirable that the ponds should be " wintered " each year — that 
is, entirely drawn off in the autumn, thus leaving the beds exposed to 
the combined action of sun, winds, and frost. This tends to kill out 
the larvse of the larger aquatic insects (dragon-flies, beetles, etc.), and 
to increase the following season's supply of small Crustacea, which fur- 
nish an important element of food to the young bass. This purifying 
process can be assisted by the free use of quicklime dropped into the 
crayfish holes. There is no danger of the lime injuring the fish the 
following year, as lime-water is more beneficial than harmful, and the 
process purifies the pond-bed, besides killing the crayfish and the like. 

In addition to the yearly wintering, the accumulated decayed matter 
ought to be occasionally removed, the frequency for this depending on 
the character of the water supply, the amount of silt it brings into the 
pond, the character of the soil, and on the thoroughness of the yearly 
removal of the surplus mosses. Scraping large ponds and hauling the 
accumulated muck involve considerable labor and expense, possibly 
more than the yield of the pond warrants, and in some cases it is advis- 
able, once in four or five years, to lay the pond bare for an entire year 
and cultivate it in peas or some other deep-rooted vegetable. 

While abundant pond vegetation is favorable to a large production of 
fry, it is sometimes so luxuriant that it settles down in a blanket-like 
mass and smothers many of the young fish. Under such circumstances 
it should be removed some time in advance of lowering the pond 
level, and during the process should be carefully picked over, as some 
of the fry will be found among it. Wading into the pond leaves the 
bottom tracked with deep footprints, which, as the water recedes, 
catch and retain many of the young fishes, most of which die in a short 
time. To avoid this a strong but lightly built flatboat is used, which 
can easily be moved from pond to pond as needed. At either end of 



170 REPORT OP COMMISSIONER OP FISH AND FISHERIES 

the boat is a ring through which a stake is driven at the point in the 
pond, to be worked. The vegetation is raked from the water in small 
lots, and unloaded on the banks with a pitchfork. It should be promptly- 
removed from the bank, as it will rot very fast and its presence is 
objectionable. 

NESTS AND NEST-BUILDING. 

Whenever the spawning period occurs, whether early or late, ample 
warning is given by the preparation of the nests, which are built by 
the mated fish, sometimes working in company and sometimes sepa- 
rately, The nests are ordinarily built in gravel, brushed into neat 
circular piles 18 inches to 3 feet in diameter, and are usually found in 
water from 18 inches to 3 feet deep, though not infrequently in much 
deeper water and sometimes in water less than a foot in depth. 

In the proper preparation of the newly built spawning-pond, clean 
gravel, ranging in size from a buckshot to a hickory nut, is arranged 
in small flat heaps about 4 to 6 feet from the banks as soon as the ice 
is off in the spring, in advance of the spawning season, and, if well 
located, it can be used through several seasons and more than once 
in the same season. Gravel probably possesses no advantage, of itself, 
over a hard clay bed except that it presents more surface within a given 
area for the eggs to attach themselves to; but if gravel of suitable size 
is to be had the bass usually select it, and no matter how dirty it may 
be, or how overgrown with moss and algae, they clean it with the caudal 
fin and tail until it is as bright as if every particle had been polished 
with a brush, often using the head and mouth to remove the larger 
stones from the nest. On the Mississippi River and in Texas, however, 
black bass have been observed to deposit their eggs on mud. 

Some bass build several nests in a season and are compelled to remove 
a comparatively large quantity of rough and jagged material, yet very 
few wounded or abraded bass are captured. At Neosho the same bass 
have been observed at nest-building for seven years without showing a 
torn or worn caudal or anal fin. Trout, on the contrary, wear their 
caudal fins and tails to the very bone in their efforts, and often die in 
consequence. Many of the wounds on the trout at spawning time are 
due as much to fighting as to the wear and tear of nest-building; and 
the bass also are hard fighters. 

The proximity of the nests to each other depends on the size of the 
pond and the number of fish. They are sometimes less than 5 feet 
apart, and in a spawning-pond of the Michigan Fish Commission, 
having only 108 square feet of surface and containing 30 adult fish, 
there were 8 nests. If the nests are placed near the banks, in water 
from 18 inches to 3 feet deep, the entire process of spawning and 
incubation is easily observed and the fry can be more conveniently 
secured and transferred to nursery-ponds at the proper time. The larger 
fish are apt to select deeper water, but they have been known to decline 
a clean lot of gravel, in water 3 feet deep and 8 feet away from the 



MANUAL OF FISH-CULTURE. 



171 



embankment of the pond, to build a nest on the naked clay bottom 
within reach of the bank on which people were passing almost every 
hour. Nesting bass should have seclusion, although those reared in 
captivity probably fail to notice minor disturbances at the time of 
spawning which would at other times alarm them. 

Artificial nests for bass have been devised, which should give 
increased results in the number of fry saved by simplifying the trans- 
fer of fry to nursery ponds and eliminating the risk of handling with 
nets. The artificial nest is a wooden box about 20 inches square, with 
sides 21 inches high and slightly flaring outward. Cleats are nailed 






"ta 






Artificial Nest for rearing Black Bass (perspective and sectional views). 

on the side for convenience in handling. Coarse gravel is placed in 
the bottom of the box and the remaining space filled with fine gravel, 
flush with the top of the box. The top layer is sufficiently fine not to 
allow the eggs to fall through the spaces and mix with the large gravel 
underneath. The nest, thus completed, is placed in an excavation with 
the upper edge even with the bottom of the pond. A stake is driven near 
the nest and a board fastened to it to afford seclusion and protection 
from the sun and enemies. A round pottery nest, about the same size, 
with a rim sufficiently high to retain the gravel, is also used. Shade is 



172 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 

important, for, although bass sometimes build nests where there is no 
shade, in most instances they select places under overhanging grasses, 
lily-pads, stumps, and logs. The artificial nests should be located 
several weeks in advance of the expected spawning, and undue dis- 
turbance of the pond should be avoided. They must be examined 
often, and all containing young fish removed to the rearing-ponds. 

From the time the bass commence nest-building the attendant keeps 
the pond and its contents under constant surveillance and maintains a 
close watch for fish-hawks and herons. A record is kept, as nearly as 
practicable, of the date when each lot of eggs is laid, so that it may 
be known when to expect the young to hatch. If artificial nests are 
used, the observations can be made more carefully, and numbers can be 
painted on the shade board to designate the particular nests, and the 
records of hatching and spawning can be kept with greater accuracy. 

STOCKING THE BREEDING-PONDS. 

Whenever procurable, domesticated fish are to be preferred to wild 
fish for this purpose, as they are less liable to injury in handling and 
transportation. A disrupted scale, lacerated fin, or a bruise on head 
or body frequently causes the death of wild bass, and the conditions of 
their native surroundings make it difficult to collect any considerable 
number of them. Moreover, adult fish captured from their native 
waters frequently fail to spawn in the year or season in which captured, 
on account of fright. 

Bass not over 2 or 2J pounds are recommended if the work is carried 
on in ponds which are to be frequently drawn off, but larger fish can 
be used advantageously if they are to be but rarely transferred to other 
ponds. Very large bass are more liable to injury when the ponds are 
drawn and the fish transferred, as they are more difficult to handle 
safely, and bruise and injure themselves in the tubs. Males and females 
should be in equal proportion, as an excess of males is liable to prove 
a disturbing element at spawning time, and, later in the season, a 
source of loss from their preying on the fry. The sexes of the black 
bass are not as easily distinguishable as of the trout. The number 
of adult fish for breeding-ponds depends upon the food supply. For 
several years past at Neosho an average of 30 breeding bass to the 
acee of water has been allowed, but that number might be increased. 

SPAWNING HABITS. 

When the nests are prepared and the spawning time arrives, the 
parent fish — especially the male — show considerable excitement and 
swim back and forth over and around the nest. In the act of spawn- 
ing they cross the nest, their bellies close together, the male a little 
behind the female, and simultaneously void the eggs and eject the 
milt, the real act of spawning occupying a comparatively short time — 
a minute or less. The eggs, when laid, are viscid, and as soon as voided. 



Report U. S. F. C. 1897. (To face page 173.) 



Plate 49. 



•*aL** 




;.* *■« / '?*■'■" 

jr.. ?* .<!.~v, 



A f 



MANUAL OF FISH-CULTUKE. 173 

and impregnated attach themselves to the floor of the nest. Then 
commences a parental watchfulness worthy of imitation on the part of 
some higher animals, one fish hovering immediately over the nest and 
maintaining a gentle motion of the fins for the purpose of keeping the 
eggs free from sediment, and the other acting as an outer sentinel, 
patrolling 8 or 10 feet away. Both male and female show great courage 
when guarding their eggs and young fry. A rock bass has been seen 
to leap entirely out of the water to bite viciously at an attendant's hand 
when moving aside the grasses sheltering the nest, and a black bass 
when guarding its nest has been known to attack and kill a snake three 
times its own length. The brightness of the nest makes the parent on 
guard easily distinguishable by enemies, like the fish-hawk and eagle, 
but this danger maybe materially lessened by planting the broader-leaf 
water-lilies near the nests to afford shelter when in danger. 

Black bass begin to spawn in the northern part of the United States 
about the middle of May, while farther south the season commences as 
early as March, and in all localities it is later in deep than in shallow 
waters. In the far South, in waters uniformly warm, the spawning 
time may not depend entirely on the seasons. The period lasts about 
two months. Many, if not all, discharge only a part of their eggs at 
one spawning. The maturation of the entire ovaries is never fully 
completed at one time, but the ripening is prolonged and the spawning 
done at intervals. As far north as southern Missouri and Illinois, 
black bass frequently spawn in the season following the spring when 
they are hatched, but this is not always the case 5 and farther north 
maturity comes later in life. Bass continue to yield eggs for a number 
of years, and there are some in the brood ponds at Neosho which were 
adults when first taken to the station, and have been held for seven 
years and are still productive, though less so than formerly. 

Bock bass have been known to produce two separate broods within 
one season as far north as southern Missouri, and this is probably true 
of some of the other basses. At Neosho they spawn when one year old. 

EGGS AND FRY. 

The eggs differ greatly in number and size, according to the age and 
size of the fish, varying generally from 2,000 to 10,000 per fish and from 
80,000 to 100,000 per quart ; 17,000 eggs have been found in a large 
mouth black bass weighing 2£ pounds, a little less than 7,000 to the 
pound of fish ; but on another occasion careful count of the mature eggs 
showed only 2,674 to the pound of fish. Wide discrepancies in the 
figures maybe sometimes accounted for by different methods of count- 
ing, as in rejecting or counting small eggs which are commencing their 
maturation for the next production. The rock-bass egg is fully three 
times as large as that of the black bass, and the fry correspondingly 
large. 

The varying factor of initial vitality and the impossibility of equal- 
izing the intensity of sunlight render it impossible to determine pre- 



174 REPORT OF COMMISSIONER OP FISH AND FISHERIES. 

cisely the period of incubation of any eggs treated in pond-culture. 
With some kinds, under extreme conditions of temperature and other 
less understood factors, wide variations are found. Bass eggs require 
from 7 days to 3 weeks for hatching, but usually from 8 to 10 days — 
governed mostly by the temperature of the water. Eggs artificially 
impregnated, in an experimental way, hatch in from 70 hours to 4 
days at a temperature of 63° F., or somewhat over. 

When the fry leave the eggs, they remain on the nest till the sac is 
absorbed, this depending, as with other fishes, on the period of incu- 
bation, modified by the temperature or condition of the atmosphere; 
usually a fifth less time being required to absorb the sac than for hatch- 
ing the eggs. When the sac is absorbed, the fry rise from the nest 
and form a school which hovers over the nest usually from two to four 
days, settling back at night, except in extremely warm weather, when 
they may scatter in a few hours. A sudden fall of temperature may 
cause the school to settle back and remain a day or two longer on the 
nest. The tactics of the parents change and they no longer stand 
guard over the nest, but circle around the school, whipping back truants 
and driving off intruders. When the school rises and hunger begins 
to be felt, the fry separate and are driven, for protection, by the parent 
fish into shoal water or into the thick grasses; there they are deserted, 
and dispersing, they seek the minute Crustacea, larvae, and insects. 

Black-bass fry do not average one-fourth of an inch in length and 
are almost colorless for the first three to five days, when the pigment 
forms along the back, making them appear quite dark when viewed 
from above, though it is difficult to distinguish the color of an indi- 
vidual fish when caught on a net of bolting-cloth. 

Very young rock bass seem occasionally to attach themselves to the 
sides and bottom of the nests and to submerged plants. This action 
has not been noticed with black bass, possibly because their nests, 
being in deeper water, are more difficult of observation. 

FOOD OF THE YOUNG. 

Just how much food to give the young bass fry is as difficult to 
determine as with any other young fish. They are very greedy, and, if 
acceptable food is given them, appear to be hungry nearly all the time, 
and it is more than probable that the troubles caused by overfeeding 
other fishes would show themselves in the bass if they were overfed. 
Bass, like the trout, are given about 1 J per cent of their weight in food 
per day. This ratio will maintain black-bass fry in a healthy growing 
state, and probably less will be found to answer with rock-bass fry. 
Compared with other fishes reared in troughs, especially some of the 
trout, bass are easily managed. Healthy fry have been carried at 
Neosho for four months with a loss of only 2 per cent. When first 
brought into the troughs, they can not be induced to take the prepared 
food, as they are wild and must be tamed or domesticated. They are 



MANUAL OF FISH-CULTURE. 175 

fed almost every hour in the day, though but little food is given at 
one time and that well scattered through the trough. The attendant 
should be about the trough constantly to accustom them to his pres- 
ence, care being taken not to alarm them. Instead of being frightened 
and darting to the dark corners of the trough at his approach, they 
soon learn to come to meet him, not a few at a time, but all together. 

For several days their food will have to consist of such minute ani- 
mals as can be conveniently collected from the ponds with a dip net of 
cheese-cloth. After four or five days they will accept prepared food, 
as fish of some .kind, ground to a fine paste. In general, bass fry under 
1| or 1£ inches in length are too small to take artificial food, and some 
die before they can be accustomed to take it. 

The number of young bass to be put into a pond depends upon its 
size and its capacity to produce food. If the nursery has been prepared 
in advance with aquatic plants some Crustacea will be found there, and 
the deficiency is supplied by the introduction of snails, Gammarus, 
Gorixa, etc. The use of beef liver as food is not advised. To a nursery in 
fair condition from 3,000 to 5,000 young bass may be allotted. The death 
of a part of these must be expected, and if even a fair percentage are 
to survive they must have more food than the pond can grow. Should 
a large part of them survive the first few weeks they can be distributed 
into other nurseries. 

At Neosho crayfish have been used for food with good results, not 
that they have any value over other forms of aquatic life, but because 
they are abundant, cost nothing, and are acceptable to the fish. Young 
bass can easily be fed on any kind of fish, and all that is necessary is 
to reduce the fish to a paste by passing it through a meat-cutting 
machine. Carp may be cultivated for the purpose. At the Forest 
ponds of the Missouri Fish Commission little branch chub are caught 
and placed in the pond several weeks before the bass spawn. As the 
chub spawn and hatch out before the bass, when the young bass are 
transferred to the nursery they find a lot of young chub ready to be 
eaten. An objection is that the old chubs destroy the young bass, 
though this could be obviated by hatching the chub artificially (as can 
be easily done) and turning only the young chub into the pond. How- 
ever, the propensity to cannibalism in the bass should not be fostered, 
and it is better not to feed bass, old or young, on any kind of live fish. 
They are thus trained, while under domestication, to forego their natural 
inclination for fish diet. 

Sometimes, even with abundance of natural food, the young prey upon 
each other, and they should then be thinned out by transferring a part 
to nursery-ponds, or the entire lot removed to troughs or vats in the 
hope of inducing them to take the prepared or natural food. As the 
summer advances the strongest fish may be observed to grow rapidly, 
and at the first evidence of unusual growth the fish must be sorted out 
and those of a certain size placed in separate ponds. The successful 



176 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 

raising of bass in ponds depends very largely on frequent and careful 
sorting, and a fish that persists in efforts to devour his companions 
should be either liberated or destroyed. 

TRANSFER OF FRY FROM HATCHING-PONDS. 

In transferring the fry to troughs or other ponds two nets of cheese- 
cloth are required. The main one is about 30 inches square, supported 
by ribs from above; to the center of the ribs a handle is attached, so 
that the net can be used 5 or 6 feet from the shore; the net is made to 
sag to an open pocket in the center, which can be closed and tied with a 
drawstring. The second net is easily made from an ordinary landing- 
net by replacing the netting with cheese-cloth. This will be useful in 
catching the fry that escape from the larger net. The transfer is made in 
tubs filled with water from the spawning-pond in order to preserve the 
same temperature as nearly as possible. Netting is done in the early 
morning, as the shallow waters of the pond become cool during the night 
and the temperatures of the different waters are more nearly equal. 

The process of netting requires patience and a degree of skill which 
comes with practice. The operator stands on the bank and introduces 
the net with a gentle and scarcely perceptible side movement under 
the school and cautiously lifts it out, and, when the net is clear of 
the water, turns with a quick motion and brings it over the tub, so that 
the part of the net holding water aud fish can be readily submerged 
in the tub. An assistant stands near the tub to catch the sides of the 
net and help in the latter part of the operation. While the operator 
holds the rod to which the frame of the net is attached, the assistant 
slips his hands into the tub and unties the drawstring of rhe net pocket, 
and the net is then gently lifted out of the tub. A bucket of water from 
the pond, and a dipper, are kept at hand to wash any of the fry into 
the tub that may stick to the cheese-cloth. The fry should never be 
freed from the uet by the use of a feather or by shaking. 

As soon as the collected fry are in the vessels they are carried to the 
troughs or pools, when the temperature of the water in the bucket 
or cans is compared with that flowing through the troughs. An 
experienced workman can tell by the sense of touch whether there is 
a material difference in the temperature, and can take the steps toward 
equalizing it. Should there be a difference of 3° or more, it must 
be corrected. If a vessel is not crowded, an effective, though slow, 
method of equalizing the temperature is to set or suspend the vessel 
in the water flowing through the pool or trough. If the water in the 
vessel is warm and the time short, in addition to setting the vessel in the 
trough, a part of the water may be bailed from the vessel and replaced 
with fresh colder water. This operation is known among fish-culturists 
as "tempering;" it requires care, good judgment, and patience. 

It is well to have several large buckets made with "windows," that 
is, a small screen of perforated metal in one side of the bucket near the 



MANUAL OF FISH-CULTURE. 177 

top. The windowed bucket is put iu a trough under a small jet of water, 
conducted by a rubber tube to the bottom of the bucket. The jet 
discharging at the bottom of the bucket, and the surplus water escaping 
through the perforated window, assist in the process of tempering. 
The temperature being equalized, the fish are carefully ladled into 
troughs or pools and the various sizes sorted and separated into different 
troughs. 

A part of the fry do not find their way through the wire screens into 
the cut-off, and all around the margin of the pond, even in the deep 
water, straggling fry may be seen. Sometimes these scattered youngsters 
will be small, but generally they are the largest. After all the fry have 
been captured from the cut-off and the season's spawning is over, the 
pond is drawn to collect and save those that have failed to come into 
the cut-off. This work is generally in June or July, when the ponds 
are quite warm and the temperature of the atmosphere is high, and is 
carried out with extreme watchfulness and care, as the midsummer 
drawing of a bass pond is the most delicate operation connected with 
their propagation in ponds. These fry need to be "tempered" and 
sorted in the same way as advised for other fry. 

During the various stages of its life the bass is subject to the attack 
of enemies of many kinds. The fish-eating birds, like the kingfisher; 
wading birds, like the heron, and amphibious animals, like the mink 
and muskrat, must be guarded against. Snakes, frogs, turtles, and 
various beetles are dangerous to the fry, and sometimes even to adult 
fish. 

SHIPPING FRY. 

Collecting for shipment occurs in the cool days of autumn, as experi- 
ence has shown that the bass can be much better and more safely 
transported in the spring and fall than in the summer. They can be 
transported more cheaply in midwinter than any other time, but when 
fish are moved long distances in very cold weather (or at any other time 
when much ice is used in the cans) many die from gill troubles. After 
the ponds are freed from vegetation and are ready for drawing off, 
the water level is reduced slowly. Every precaution is taken not to 
frighten the fish, and with this in view no more attendants are allowed 
about the bank than are absolutely necessary. Black bass when 
frightened will burrow in the mud and live there an incredible length 
of time, and if a fingerling burrow in the mud when the pond is being 
drawn he may prove a dangerous occupant the following spring when 
the young fry are introduced. The same precautions should be observed 
in transferring fingerlings as with the very young fry. 

F. C. E. 1897 12 



Report U. S. F. C. 1897. (To face page 179.) 



Plate 50. 




% £< 



MISCELLANEOUS FRESH-WATER FISHES. 



Besides the fresh-water and anadromous fishes considered in the fore- 
going chapters, a number of others have been artificially cultivated, 
including some species introduced from Europe. The special methods 
of propagation already referred to are in general applicable to all fishes 
of similar character, and need not be described again in detail. 

MINOR TROUTS AND THE GRAYLING. 

The different methods of hatching the eggs of the various members 
of the salmon family are practically interchangeable, so that in con- 
sidering the following species it is not necessary to dwell again on 
fish-cultural processes. 

Several varieties of the black-spotted trout (Salmo mylciss) are artifi- 
cially propagated. This fish is somewhat similar to the European sea 
trout or salmon trout (Salmo trutta) and in parts of its range has the 
same ha If- migratory habits. It is widely distributed, very abundant, 
and subject to great variation in color and structure. It is found from 
Alaska to Mexico in the streams of the Coast Eange, Sierra Nevada, and 
Eocky Mountains, and in some lakes in the same regions. It attains a 
weight of over 30 pounds, although the average is, of course, much less. 

Among the varieties whose eggs have been artificially hatched are 
the Lake Tahoe trout or Truck ee trout (Salmo myMss henshawi), which is 
extensively propagated by the California Fish Commission at hatcheries 
on Lake Tahoe; the Colorado Eiver trout (Salmo myMss pleuriticus), 
and the yellow-fin trout (Salmo myMss macdonaldi), both of which are 
cultivated by the U. S. Fish Commission at its station at Leadville, 
Colorado. All of these species are handsome game and food fishes. 

In the vicinity of Leadville the spawning season extends from May 1 
to July 15. The eggs are hatched in the same troughs and under the 
same conditions as those of the brook and rainbow trouts. In water 
ranging from 42° to 60° and averaging about 52° F., the eye-spots 
appear in 20 days and hatching ensues in 30 to 45 days. 

The Scotch lake trout, or Loch Leven trout (Salmo trutta levenensis), 
and the European brown trout or brook trout, or Von Behr trout (Salmo 
fario), were introduced by the Fish Commission a number of years ago, 
and have been widely distributed in the United States. They are now 
propagated in many States from eggs taken from brood fish retained 
in ponds. At ISTorthville the spawning season of these fish is the same 

179 



180 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 

as that of the brook trout. Their eggs are somewhat larger than those 
of the latter fish, but they are handled in the same way, the progress 
of incubation is similar, and the fry are fed on the same materials. 

Small numbers of the European sea trout or salmon trout (Salmo 
trutta) have also been propagated at Craig Brook and other stations, 
and have been reared to full maturity in ponds. 

The fish called the Swiss lake trout, European charr, or saibling 
(Salvelinus alpinus), has been propagated on a small scale from eggs 
taken from pond fish, which in turn were hatched from eggs sent from 
Switzerland. This species is similar to the brook trout and other 
native charrs, and its eggs are subjected to the same methods. 

The representative of the saibling found in certain New England 
lakes, known as the Sunapee trout, or golden trout [Salvelinus alpinus 
aureolus), has also received some attention from fish-culturists. 

The Michigan grayling (Thymallus ontariensis) is naturally found 
only in certain streams in Michigan, although the type specimen was 
said to have come from Lake Ontario. It is one of the most attractive 
and game of fresh-water fishes, but is rapidly approaching extinction, 
owing to excessive fishing and the pollution of streams, which have not 
been counteracted by artificial propagation. The Montana grayling 
[Thymallus ontariensis montanus) inhabits a limited area in the head- 
waters of the Missouri Eiver and is very abundant in some streams. 

The Arctic grayling ( Thymallus signifer) is found from the Mackenzie 
Eiver westward through Alaska and north to the Arctic Ocean. The 
Michigan grayling rarely weighs 1£ pounds, and the average weight is 
only half a pound; the northern species is somewhat larger. 

Although the»cultivation of the grayling was begun as early as 1874, 
it was never regularly or extensively conducted. Spawning in Michi- 
gan occurs in April, and the eggs are normally laid in gravel beds in 
clear, cold streams. The number of eggs taken from a single fish varies 
from 3,000 to 4,000. The same methods of culture pursued with the 
brook trout are applicable to the grayling. In water having a tempera- 
ture of 50° to 60° F., the incubation period is 14 to 20 days. 

THE LAKE HERRING AND OTHER WHITEFISHES. 

While the common whitefish is the only member of the tribe that has 
received much attention from fish-culturists, it is probable that several 
other species of whitefish will in time be extensively propagated. The 
lake herring (Argyrosomus artedi) has already been artificially hatched 
to a limited extent at Put-in Bay station, and the long-jaw or bloater 
[Argyrosomus prognathus), the bluefin or blackfin (A. nigripinnis), the 
tullibee (A. tullibee), and others will doubtless become the subjects of 
fish-cultural work in certain lakes. The eggs of all these fish can be 
hatched by the same methods as are used with the common whitefish, 
but the spawning seasons differ. 

The lake herring is readily distinguished from the common whitefish 
by its smaller size, projecting lower jaw, long and numerous gillrakers, 



Report US F. C. 1 897. (To face page 181.) 



Plate 51, 





WM///A 




MANUAL OF FISH-CULTURE. 181 

absence of arch on back, etc. It is the most abundant of the white- 
fishes, being especially numerous in lakes Erie, Michigan, and Huron, 
and larger quantities are taken each year than of all other species 
combined. The average length is 12 to 14 inches and the average 
weight is under a pound, although a maximum weight of 3 or 4 pounds 
is attained. The fish is generally known as " herring " but has numer- 
ous other names, among which are cisco, blueback herring, greenback 
herring, grayback herring, and Michigan herring. 

The spawning season of the lake herring begins somewhat later and 
terminates sooner than that of the whitefish. The eggs are procured 
and hatched in the same manner as are those of G. clwpeiformis, and 
require about the same time for incubation, namely, 4 to 5 months, 
depending on the temperature of the water. The eggs are smaller than 
those of the common whitefish, 70,000 making a fluid quart. 

These two species are readily hybridized artificially. The milt of 
either species will impregnate the eggs of the other as effectively as if 
there were no cross fertilization. Large specimens of apparently hybrid 
fish of this character have been obtained in Lake Erie. The use of 
milt of the lake herring for impregnating whitefish eggs is resorted to 
only when the eggs would otherwise be lost. 

The round whitefish or menominee (Goregonus quadrilateralis) is 
propagated by the New York Fish Commission. It is very widely 
distributed, ranging from New Brunswick to Alaska, and is abundant 
in some of the Adirondack lakes, where its eggs are taken and hatched 
in comparatively large numbers. It rarely exceeds a pound in weight, 
but its food qualities are good, and it is taken for market in considerable 
quantities in lakes Huron and Michigan. 

In the New York lakes, where the fish is known as the frostfish, the 
spawning season is from the middle of November to the early part of 
January, although the period in any one lake is less prolonged. The 
eggs are heavy, adhesive, and £ inch in diameter; the average yield per 
fish is 3,500, but 12,000 have been taken from a If -pound fish. In the 
very cold water of these lakes the incubation is protracted, being 150 
days with the water at 33° F. The sac is absorbed in 10 to 20 days. 

THE MUSKELLUNGE. 

The muskellunge (Lucius masquinongy) is the largest representative 
of the pike family. Its maximum weight is about 80 pounds and its 
average weight 25 or 30 pounds. Its range includes the Great Lakes, 
Upper Mississippi Valley, Ohio Valley, and lakes in Wisconsin, Minne- 
sota, New York, Ontario, and elsewhere. It is much sought by anglers 
and is of some value as a food fish. Being provided with a very large 
mouth, armed with strong, formidable teeth, its food consists chiefly of 
living fish, which it captures by making sudden darts from its place of 
concealment among the water-plants at the bottom of a lake or stream. 

This fish is artificially propagated by the New York Fish Commission 
at Chautauqua Lake. Upward of 3,000,000 fry are sometimes hatched 



182 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 

in a year. The eggs are taken from fish caught in the lake, and are 
hatched in submerged boxes, provided with double wire-mesh tops and 
bottoms. The eggs are similar to whitefish eggs, being semibuoyant 
and noDadhesive. A 39J-pound fish has been known to have ovaries 
weighing 5 pounds, and a 35-pound fish has yielded 265,000 ripe eggs. 
Spawning takes place in May, in shallow, grassy places. The eggs 
are about -^ of an inch in diameter and number 74,000 to the quart. 
About 97 per cent of the eggs impregnated are hatched. With the 
water temperature at 55° F., hatching ensues in 15 days, the yolk-sac 
being absorbed in the same time. The fry are very helpless when first 
hatched. 

Owing to the extremely voracious habits of the muskellunge, great 
caution should be exercised in distributing the fry, which should, as 
a general practice, be placed only in those waters in which the fish 
already exists. 

THE YELLOW PERCH. 

The yellow perch (Perca flaveseens), known also as ring perch, striped 
perch, and raccoon perch, is one of the most strikingly marked and best 
known freshwater fishes of the Atlantic and North-central States. It 
is commonly regarded as the type of the spiny-rayed fishes and in some 
systems of classification is given the first place among fishes. 

The general body color is golden yellow, the back being greenish and 
the belly pale; six or eight broad vertical blackish bars extend from the 
back nearly to the median line of abdomen; the lower fins are largely 
bright red or orange, most highly colored in the breeding male; the dor- 
sal fins are dull greenish. The body is elongated, back arched, mouth 
large and provided with bands of teeth on jaws, vomer, and palate. 

It is found from Nova Scotia to North Carolina in coastwise waters, 
throughout the Great Lakes, and in the Upper Mississippi Valley, and 
in most parts of its range is very abundant. Through the efforts of 
the Commission it has been very successfully introduced into lakes 
in California, Washington, and other Western States, and is now met 
with regularly in the markets of some of the cities of that region. 

The usual length of the yellow perch is less than 10 inches, and its 
average weight is under a pound. It is a food-fish of fair quality, and is 
taken for market in very large quantities annually in the Middle States 
and Great Lakes, fyke nets, gill nets, seines, traps, and lines being used. 
The value of the output is over $300,000 yearly, more than a third of 
which sum represents the fishery in the Great Lakes. It bites readily 
at the baited hook and is caught in large quantities by anglers. 

Artificial propagation, in the full sense of the term, has not been 
attempted with the yellow perch. The eggs have neither been artifi- 
cially taken nor artificially impregnated, but the brood fish have been 
impounded and their naturally fertilized eggs hatched. The extent to 
which this modified cultivation of yellow perch may be carried on in 
the coast rivers, in the Great Lakes, and elsewhere is almost limitless. 



MANUAL OP FISH-CULTURE. 



183 



The fish is so abundant, however, and the supply so well maintained 
that fish-cultural work in its behalf is not now generally required. 

This fish spawns in late winter and early spring in the fresh waters 
of the coast rivers and in the Great Lakes. In the Potomac Eiver 
spawning takes place in February, March, and April. The water tem- 
perature at which spawning begins is about 44° F., while 49° seems to 
mark the maximum limit. This narrow range of temperature which 
bounds the spawning act is somewhat noteworthy. 




Ovary of a yellow perch with nearly-ripe eggs, the forked 
extremity being the anterior part of the roe. 

The eggs of the yellow perch are among the most remarkable that have 
been artificially hatched. The spawn is in one piece, a much elongated 
ribbon-like structure, of a semitransparent light-grayish color. One 
end of the large egg mass, corresponding to the anterior part of the roe, 
is larger than the other, and is bluntly forked. The string is very long, 




Part of a recently-laid mass of yellow-perch eggs. 

but may be much compressed lengthwise by virtue of its arrangement 
in regular transverse folds like the sides of a bellows or accordeon. 
When deposited the eggs are in a loose globular form, and after being 
fertilized and becoming "water-hard" their mass rapidly becomes many 
times larger than the fish which laid them. The length of the strings 
is from 2 to more than 7 feet, depending on the size of the fish. One 



184 REPORT OF COMMISSIONER OP FISH AND FISHERIES. 

fish in an aquarium at Washington deposited a string of eggs 88 inches 
long, 4 inches wide at one end and 2 at the other, whose weight after 
fertilization was 41 ounces avoirdupois, while the weight of the fish 
before the escape of the eggs was only 24 ounces. 

A cavity extends the whole length of the egg mass, its walls being 
formed by the delicate membrane in Avhich the eggs are imbedded. The 
cavity is almost closed, small apertures occurring irregularly, which 
have the appearance of being accidental, but may be natural, in order 
to permit the circulation of water on the inside of the mass. 

The egg-string is quite light and resilient or springy, the least agita- 
tion of the water causing a quivering motion of the whole mass. 

The diameter of the egg is -^ inch. The quantity can not be easily 
measured, but the number is approximately 28,000 to a quart. 

The best method of securing the spawn is to place mature fish of 
both sexes in suitable tanks with running water. The females selected 
should be those whose external appearance indicates that the eggs 
are still undeposited. Spawning takes place at night, and the eggs are 
naturally fertilized. Under proper conditions, it is the exception to 
find unfertilized eggs. In the morning the eggs are transferred to the 
hatching apparatus. 

The eggs of this fish have been hatched at different stations of the 
Commission. One season, at Central Station, Washington, D. C, 130 
ripening females and about an equal number of males taken from the 
Potomac were placed in aquarium tanks supplied with water from the 
city water- works. Spawning began March 10 and continued till April 3, 
and 98 strings, containing nearly 1,000,000 eggs, were deposited. 

The eggs are hatched in the automatic shad jar, provided with a cap 
of fine-meshed wire netting; the usual inflow tube is retained, but the 
siphon tube is withdrawn, the water escaping over the top of the jar. 
The amount of water circulation is not great enough to force the mass 
of eggs to the upper part of the jar or to give much motion to them. 
They are lighter than shad or whitefish eggs, and when put in rapid 
motion to dislodge adhering sediment they would clog the outlet tube 
if the ordinary method of manipulating this jar were employed. 

The eggs from several fish may be placed in one jar. They perhaps 
need as little care as any eggs handled by fish-culturists. When one 
string of eggs or one lobe of a string dies it may be removed with a 
small net, or the entire contents of the jar may be turned into a pan. 

The period of hatching varies from two to four weeks, according to 
the temperature. As the fry hatch, they pass over into tanks provided 
with screened overflows, where they are held till planted. The fry are 
very hardy, and may be readily retained in aquaria for several weeks. 
The percentage of eggs hatched is large. From one lot of 955,000, 
754,000 fry, or 79 per cent, were produced. 






MANUAL OF FISH-CULTURE. 185 

THE STRIPED BASS AND THE WHITE PERCH. 

The striped bass, or rockfish (Boccus lineatus), ranges from New 
Brunswick to western Florida. It is especially abundant from New 
York to North Carolina, and is taken in large quantities for market, by- 
means of seines, gill nets, pound nets, and lines, on the coast and in 
the bays, sounds, and rivers. It is one of the best food-fishes of 
American waters. The annual value of the catch is about $300,000. 

Through the efforts of the Commission, this fish has been introduced 
into the waters of California, where it has become very abundant; it 
occurs along almost the entire coast of that State, but is most numerous 
in San Francisco Bay and tributaries. It supports a special fishery, 
and the estimated catch in 1897 was about 1,000,000 pounds. It meets 
with ready sale, and is one of the most popular fishes of the west coast. 

The striped bass attains a weight of over 100 pounds; examples 
weighing 50 to 75 pounds are not uncommon ; but the usual size of those 
taken for market is 3 to 20 pounds. Its form, size, and markings make 
it readily distinguishable from other fishes. The color of the body 
is light silvery-green above, white below, with seven or eight blackish 
stripes along the sides. 

The striped bass passes most of its time in salt water, but in spring 
ascends the rivers to spawn. Important spawning-grounds are the 
tributaries of Albemarle Sound, Chesapeake Bay, Delaware Bay, and 
New York Bay. The eggs are sometimes deposited quite near the ocean, 
in brackish or salt water. The number that may be deposited by a 
single fish is immense; a fish weighing only 12 pounds, caught at the 
mouth of the Susquehanna River, in May, 1897, yielded 1,280,000 good 
eggs, and a 75-pound fish would doubtless produce 10,000,000 eggs. 

The commercial importance of the striped bass and its comparative 
scarcity in some waters in which it formerly abounded make its culti- 
vation very desirable, and its eggs have been artificially impregnated 
and hatched on several occasions; but difficulty has been experienced 
in finding a locality where ripe eggs can be regularly taken in large 
quantities. The eggs are free, transparent, and semi-buoyant, about 
\ of an inch in diameter, and have a very large oil- globule. In quiet 
water they gradually sink to the bottom of a vessel and remain there, 
but a very slight agitation of the water causes them to rise and remain 
in suspension for some time. The number in a quart is about 24,000. 

The tidal apparatus, such as is used for cod and tautog eggs, is 
adapted to hatching the eggs of this fish. At a mean temperature 
of 58° F., the hatching period is about 74 hours. A large oil-globule in 
the anterior part of the yolk-sac causes the younger fry to assume a 
perpendicular position, with the head toward the surface of the water. 

The white perch (Morone americana) belongs to the same family as 
the striped bass, and closely resembles it in range, habits, and character 
of the eggs; but it is much smaller and less valuable commercially, 



186 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 

although one of the choicest of pan fishes. Its eggs are deposited about 
the same time and in the same places as those of striped bass and are 
susceptible of the same methods of hatching. Ripe fish are frequently 
taken in shad seiues. The average yield of eggs per fish is about 
40,000. The period of incubation is like that of the striped bass. 

THE ALEWIVES OR RIVER HERRINGS. 

The alewives or river herrings have the appearance of being small- 
sized shad, but on close inspection will be seen to have characters which 
entitle them to geueric distinction. From the shad {Alosa) they differ 
chiefly in having the cheeks longer than deep, fewer and shorter gill- 
rakers, and no notch at the tip of the upper jaw. They also closely 
resemble the common sea herring (Olupea), but may be distinguished 
from it by the absence of teeth on the vomer, by a less elongate body, 
and by much stronger scutes or plates along the ventral edge of the 
body. The two species of alewives so closely resemble each other that 
they are often confounded by fishermen. 

The branch herring (PomoloMis pseudoharengus), also known as the 
branch alewife, gaspereau, wall-eyed herring, etc., has a rather deep 
and compressed body (the depth being contained 3J times in length), 
a large eye, and a pale or gray membrane (peritoneum) lining the 
abdominal cavity. The glut herring (Pomolobns aestivalis), also called 
blueback, sawbelly, kyack, summer herring, etc., has a more elongate 
body, smaller eye, lower fins, and a dark or black peritoneum. 

The alewives are the most abundant food- fishes of the east coast 
rivers and rank next to the shad in commercial value among the 
anadromous fishes of the Eastern States. Both species range along 
the entire Atlantic coast of the United States, but the glut herring is 
more numerous southward and the branch herring is the principal fish 
in New England. The average weight of each species is one-third to 
two-fifths of a pound. The maximum is only half a pound. The age 
at maturity is three or four years. 

There is an alewife fishery in every coast State from Maine to Florida, 
but two-thirds of the catch is taken in Maryland, Virginia, and North 
Carolina, Chesapeake Bay and Albemarle Sound being the chief cen- 
ters of abundance. The total output in 1896 was 62,066,622 pounds, 
having a value of $459,598. These fish usually go in large schools or 
bodies, which are often of immense size. Many hundred thousand 
have frequently been taken at a single seine haul, and they have at 
times been so abundant in North Carolina and elsewhere as to crowd 
out shad and other fish and cause a suspension of shad fishing. 

Besides furnishing food for man, in a fresh, pickled, and smoked con- 
dition, alewives are consumed in large quantities by other food-fishes, 
especially in salt water, and are extensively utilized as bait in the 
important line fisheries of New England. 

The annual migration of the alewives from the ocean to the fresh- 



MANUAL OF FISH-CULTUKE. • 187 

water rivers is wholly for the purpose of spawning. The time of their 
arrival in a given place is quite constant from year to year. The 
branch alewife precedes the summer alewife by three or four weeks, 
and also arrives several weeks before the shad. The run of the glut 
herring occurs during the middle of the shad season. The branch 
herring ascends the small streams to spawn, often entering branches 
only 10 feet wide and not more than 6 inches deep. After spawning, 
very little is known of the habits of the fish or of the departure from 
the rivers ; nor has their winter abode been ascertained. 

The eggs resemble those of the sea herring rather than of the shad, 
being glutinous and adhering to brush, stones, piling, and other 
objects under water. The netting, ropes, and stakes of traps in which 
the fish are caught are often covered with the fertilized eggs ; the ale- 
wives thus have a great advantage over the shad, and to this fact 
must largely be attributed the continuance of the supply in the face of 
very extensive fishing not counteracted by artificial propagation. The 
eggs are about - 2 - - inch in diameter. 

There has been no effort to regularly hatch the eggs of ale wives 
artificially. The undiminished abundance of these fish in the regions 
of the most extensive fisheries has made their artificial propagation 
unnecessary. In the New England States, where the alewife is an 
important fish in many of the smaller towns, the supply has been 
maintained by constructing fishways which permit the fish to reach 
their spawning- grounds. In this way comparatively small streams have 
annually yielded very large quantities of fish, and many streams, in 
which the alewife run had been entirely inhibited by obstructions, have 
been reopened and very successfully restocked. 

As early as 1871 the eggs of the alewife were artificially fertilized 
and hatched, and those of the branch herring were similarly treated in 
1877. Their cultivation presents no special difficulties, and can be 
prosecuted on a large scale whenever it becomes necessary. The milt 
is first taken in a pan, and then, while one person keeps the pan in 
motion, another expresses the eggs; this prevents the eggs from mat- 
ting together and facilitates the contact of all with the milt. Eggs 
adhering to the side of the pan may be removed with a stream of water. 

The automatic shad jar is the proper apparatus in which to hatch the 
eggs, which are treated precisely like those of the shad. Sufficient 
water is supplied to keep them moving freely and to overcome adhesion. 

The alewives are much more prolific than either the shad or the sea 
herring. On one occasion, in the Potomac Eiver, 644 female branch 
herring yielded 66,206,000 eggs, an average of 102,800 per fish. Prob- 
ably 100,000 may be taken as a fair average. The eggs hatch quite 
quickly under normal conditions. The period of incubation, in water 
having a mean temperature of 60° F., is 6 days. The fry are very 
minute. They are planted at the same time and in the same manner 
as shad fry. Those in the rivers and lakes attain a length of 2 to 3 
inches by the time they move toward salt water in the fall. 



188 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 

THE SMELT. 

This fish ( Osmerus mordax) is propagated by the New York Fish Com- 
mission at its station at Cold Spring Harbor, Long Island. As a food- 
fish, it is held in high esteem, the flesh being delicate and of excellent 
flavor. Its range is from Maine to Virginia, on the United States coast. 
It is of economic importance in all the States between New York and 
Maine, but is taken for market in largest quantities in Maine. The 
average length of those sold is 6 to 9 inches, and their weight from 2 to 
4 ounces. The fish enters the fresh-water rivers in fall and winter for 
the purpose of spawning and feeding and is then caught with lines and 
nets. The annual catch is about 1,700,000 pounds, valued at $125,000. 

The smelt spawns in spring, in either fresh or brackish water of 
rivers or brooks. The eggs, which are adhesive, are attached to stones, 
weeds, sticks, or other objects. 

The results of smelt propagation on Long Island have been quite 
marked; not only has there been a large increase in the catch, but the 
fish have appeared in streams where they were previously unknown. 
The return of mature fish apparently artificially hatched has permitted 
the taking of many more eggs than was at first possible. In a stream 
previously destitute of smelts, in which fry were planted in 1885, nearly 
32,000,000 eggs were collected in 1894. 

The eggs are 0.05 inch in diameter and number 496,000 to the fluid 
quart. Smelt weighing only 2 ounces yield from 46,000 to 50,000 eggs. 
Some fish only 3 or 4 inches long are full of spawn. 

The fish-cultural work with this species is similar to that with the 
yellow perch and flatfish. The spawning fish, of both sexes, are placed 
in troughs, which are covered to exclude light. The eggs are naturally 
laid and fertilized, and become attached to each other and to the 
troughs. They are scooped up with a flat shovel, placed on wire trays 
in water, and are forced through the meshes of the trays to separate 
them, the operation being repeated if they are not sufficiently separated 
at first. They are then transferred to automatic shad jars, blanketed 
to exclude light, which is very injurious to them. If during hatching 
the eggs form into bunches, they are removed from the jars and again 
passed through the meshes of the wire trays. 

THE GOLDEN IDE. 

This fish, known as the golden ide or orfe (Idus idus), has been 
introduced into the United States from Europe by this Commission. 
Although a food-fish of fair quality, it is seldom eaten in this country, 
but is chiefly used for ornamental purposes. Its usual length is about 
a foot and its weight 1 pound. It is a very showy fish, being of a uni- 
form reddish- golden or silvery color. The small, weak mouth restricts 
the character of the natural food to vegetable and diminutive animal 
substances. 

The fish is reared in ponds, like carp, tench, and other similar species. 
The ponds should be 3 or 4 feet deep, with either spring or running 



MANUAL OF FISH-CULTURE. 189 

water, and must have a very abundant growth of myriophyllum or 
other water plants. In the latitude of Washington, D. 0., spawning 
takes place in April. The fish makes no nest, but deposits its eggs on 
water-plants, gravel, stones, and other substances. The eggs being 
adhesive, like those of most cyprinoid fishes, become attached as soon 
as ejected, and so remain until hatched. The eggs are about n,- inch in 
diameter. They are extremely tender, and it is important that at the 
time of spawning the water be of an even temperature. 

Under favorable conditions the eggs develop rapidly, and at a mean 
temperature of 56° F. hatch in 5 or 6 days. In suitable ponds, with 
plenty of shade and a healthy growth of plants, the natural food that 
the fry will secure renders artificial feeding unnecessary for a month or 
more. After the fifth or sixth week the young may be given small 
quantities of cooked corn-meal mixed with flour. They take finely 
divided fish flesh, bivalves, and crayfish, but the main dependence 
should be on the corn-meal flour mixture. 

At the end of six months the young have attained a length of 3 inches, 
and in a year are 6 inches long. Maturity is attained at an age of 3 
years. 

THE STURGEONS. 

There are six species of sturgeon in the waters of the United States. 
The common and the short-nose sturgeons (Acipenser sturio and A. 
brevirostris) are found only on the Atlantic Coast, ascending rivers to 
spawn. The white sturgeon and green sturgeon (A. transmontanus and 
A. medirostris) inhabit only the waters of the Pacific Coast. The lake 
sturgeon or rock sturgeon (A.rubicundus) exists in the Great Lakes, the 
Upper Mississippi Valley, and other northern interior waters. The 
shovel-nose sturgeon or white sturgeon (Scaphirhynclius platyrhynchus) 
is found in the Mississippi and other streams of the Southern and 
Western States. 

While all of the sturgeons are edible and caught for market, the 
most valuable species are the common sturgeon and the lake sturgeon, 
which alone have been artificially propagated. 

The catching of sturgeon for market is a business of comparatively 
recent origin. A few years ago enormous numbers were annually killed 
and thrown away by salmon, shad, and whitefish fishermen, to whom they 
were of no value. The special apparatus employed in taking sturgeon 
consists of gill nets and set lines, but many are caught in pound nets, 
seines, etc., set primarily for other fish. The principal fisheries are in 
the Great Lakes, Delaware River, and Sacramento River. The present 
yearly value of the yield is about $300,000. Very important secondary 
products are derived from the sturgeon, namely, caviar, isinglass, and oil. 

The sturgeon fishery is declining, and aifords a remarkable illustra- 
tion of the comparative facility with which the supply of river and lake 
fishes may be exhausted by indiscriminate fishing. In some localities 
the change in the sturgeon fishery within a single decade has been from 
a condition of great abundance, with little appreciation of the value of 



190 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 

the fish, to active prosecution of the fishery without regard to season, 
age, or spawning state, resulting in practical extermination and the 
suspension of fishing operations. Considering the entire country, it is 
estimated that during the past decade the decrease in the sturgeon 
catch has been 60 to 80 per cent. Much of the decline in some places 
is attributable to the destruction of the young, which linger near the 
mouths of rivers and, becoming entrapped in nets and pounds, have been 
killed on account of the annoyance caused the fishermen. 

The common sturgeon of the Atlantic Coast attains a weight of over 
500 pounds, but the average in recent years is not more than 150 pounds. 
The lake sturgeon reaches a weight of about 200 pounds ; the average 
at the present time is 60 pounds. The known maximum weight of the 
Pacific white sturgeon is 848 pounds, and those weighing 500 pounds 
or more were not rare in the Columbia Kiver some years ago, when the 
average weight was fully 150 pounds ; but at present, as well as in the 
Sacramento Eiver, the average is much less. 

The spawning time of the sturgeon is spring and summer. When 
fully mature, the ova constitute from 20 to 30 per cent of the total 
weight of the female. When ripe, the eggs are free from the ovarian 
walls and lie loose in the abdominal cavity. The number of eggs pro- 
duced by the common Atlantic sturgeon is from 1,000,000 to 2,500,000. 
The spawning of the anadromous species takes place in either the fresh 
or brackish waters of the streams. The lake sturgeon prefers rocky 
ledges near the shores of lakes. When deposited naturally the eggs 
soon become glutinous and adhere to sticks, weeds, brush, and other 
objects. The diameter of the egg is ^ inch. 

The culture of the sturgeon has not been systematically carried on in 
the United States or Canada, although the time seems opportune for 
rendering aid to nature in order to keep up the supply. Experimental 
work indicates that there are no insurmountable obstacles in the way 
of extensive artificial propagation, although the work presents some 
unusual difficulties. 

One of the drawbacks met with in the Atlantic rivers is that of 
obtaining ripe male and female fish simultaneously. The important 
fact has been determined, however, that both eggs and milt may be 
cut from live or recently killed fish and fertilization be thus successfully 
accomplished. In order to secure the milt, pieces of testes may be 
obtained and the milt squeezed therefrom through a coarse cloth. 

A large proportion of the females taken at the fishing centers are 
not ready to spawn when caught, and their retention in the crude pens 
used by the fishermen, together with the rough handling they receive, 
appears to render their eggs iucapable of fertilization. The successful 
penning of the fish pending the ripening of the eggs and milt would 
greatly add to the success of this work, as the spawning season in a 
given place usually extends over a number of weeks. 

The glutinous nature of the sturgeon's egg has been a drawback in 
the propagation experiments heretofore conducted. The eggs become 



MANUAL OF FISH CULTURE. 191 

viscid in about 20 minutes after fertilization and stick together in 
masses of various sizes. This interferes with their aeration, lowers the 
vitality, and leads to the attack of fungus. The practice heretofore 
adopted for overcoming this condition has been either to spread the eggs 
in very thin layers on the hatching-trays prior to the development of 
the adhesive quality, so that after becoming fixed they would be properly 
aerated, or to stir them continuously for several hours in order to over- 
come their adhesiveness. The high degree of success attending the 
hatching of the glutinous eggs of the flatfish and the wall-eyed pike 
indicates that the difficulty encountered with the similar sturgeon egg 
may be readily overcome. By gently stirring recently fertilized eggs 
with a mixture of dry cornstarch and water or fine_swainp muck and 
water, the tendency of tbe eggs to stick together and to other objects 
is avoided through the partial coating of the individual eggs with 
particles of starch or dirt. Other substances that will remain suspended 
and not be dissolved in water can doubtless be employed to advantage. 
Swamp muck is probably the best, because cheapest and most easily 
obtained; 2 quarts of it may be mixed with 10 gallons of water, which 
will be sufficient to render non-glutinous about 3 gallons of eggs; the 
same proportion of water, eggs, and cornstarch is recommended. After 
being transferred to the hatching station, the eggs maybe placed under 
running water and the superfluous foreign particles washed away before 
being placed in the hatching apparatus. 

The apparatus used in hatching sturgeon eggs has been chiefly boxes 
placed in the open water of the river. The glutinosity being overcome, 
there seems no reason why hatching may not be conducted in the auto- 
matic shad jar or in other modern appliances. 

In the experimental hatching operations many eggs have been lost 
through attacks of fungus, induced by the character of the apparatus 
employed. The use of floating-boxes in open water has led to the loss 
of eggs by storms, rough water, and sudden changes of temperature. 

The incubation period is about 7 days in water having a temperature 
of 62° to 66° F. The outline of the fish appears in 48 hours. 

Tbe question as to whether eggs of the common sturgeon can best 
be hatched in fresh or brackish water is not yet determined, but the 
indications are that brackish water is preferable. One reason is that 
the eggs are less liable to attacks of fungus in such water. 

An attempt to rear artificially hatched sturgeon at Northville was 
unsuccessful, owing to the failure of the young to eat. The mouth of 
the sturgeon fry is very small, and the food is largely of a microscopic 
character, consisting of unicellular algse, infusoria, insect larvse, etc. 

In Europe, where the sturgeon fisheries are vastly more important than 
in America, the results of experiments in sturgeon-culture have scarcely- 
been as satisfactory as in this country. No method of separating gluti- 
nous eggs except by stirring seems to have been deyised, and the same 
difficulty has been found in obtaining fish with ripe spawn and milt. 
The retention of fish in inclosures has not generally been successful. 



Report U. S. F. C. 1897. rTo face page 193.) 



Plate 52. 




THE COD. 



DESCRIPTION OF THE FISH. 

The body of the cod is moderately long, compressed and tapering 
behind; the greatest depth is about one-fourth its length. The large 
head is narrowed anteriorly and is contained 3^ to 4£ times in the 
body length. The mouth is large; the lower jaw is included within 
the upper when the mouth is closed ; the maxillary extends to about 
middle of eye. The diameter of the eye is about half the length of the 
snout and one-fifth that of the head. There is a conspicuous barbel on 
the chin. The number of dorsal fins is 3 and of anal fins 2; the 
dorsal rays are usually about 14, 21, and 19 in the respective fins, and 
the anal rays are 20 and 18. The ventral fins are well developed, with 
about 7 rays. The cycloid scales, with which the body is covered, are 
very small. The air-bladder is large and thick. The color varies 
greatly, depending on food, kind of bottom on which found, and other 
conditions. Fish taken offshore in deep water are -usually olivaceous 
on the back and whitish beneath ; the so-called rock cod, found in shoaler 
water among rocks and kelp, vary in color from green to deep red. The 
back and sides are covered with small, round, reddish-brown spots. 
The lateral line is conspicuous, of a whitish color. The fins are dark. 

From other species of the family, taken in the same waters, the cod 
is readily distinguished. From the haddock it differs in having a pale, 
instead of a black, lateral line; in its spots (absent in the haddock), 
and in its larger maxillary bone, which reaches past the eye, while in 
the haddock this bone does not extend to the eye. The features dis- 
tinguishing the pollock from the cod are the smaller size, the projecting 
lower jaw, the uniform coloration above, the sharp snout, the smaller 
barbel, etc. The hakes have only 1 anal and 2 dorsal fins, a filamentous 
prolongation of the first dorsal ray, and a ventral fin consisting of two 
or three very long filamentous rays. 

The status of the cod of the North Pacific Ocean is somewhat uncer- 
tain. It has generally been considered identical with the Atlantic 
species, but its smaller air-bladder and other features may entitle it to 
recognition as a distinct species. 

RANGE, MOVEMENTS, FOOD, ETC. 

Cod are widely distributed in the North Atlantic Ocean. To the 
north they range far beyond the Arctic Circle, and to the south as far 
as Cape Hatteras, although they are not common south of New Jersey. 

F. C, B, 1897—13 193 



194 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 

The cod of the North Pacific Ocean is found from Bering Sea south to 
Oregon and Japan. 

The movements of cod are not well understood. They go in schools, 
but in much less dense bodies than do mackerel, herring, and men- 
haden, and when moving from one ground to another they are in more 
compact schools than when on the feeding-grounds. The movements 
on and off shore and from bank to bank are due to several causes, 
among which are the effects of water temperature, the presence or 
absence of food, and the spawning instinct. In the winter months 
there is a well-marked movement of large bodies of codfish to the 
shores of the New England and Middle States, and important fisheries 
are there carried on in regions from which cod are absent at other 
times. This movement seems to be chiefly for the purpose of finding 
shallow grounds for spawning. That the cod sometimes makes very 
long journeys is shown by their capture on the New England coast 
with peculiar hooks in their bodies which have been identified as 
similar to the hooks employed by the French cod fishermen on the 
Grand Banks. 

Although sometimes found in shallow water, cod are essentially deep- 
water fish, preferring water from 20 to 70 fathoms deep and being 
found even at a depth of 300 fathoms. Those caught for market are 
usually taken at depths of 20 to 40 fathoms. 

The cod takes its food on the bottom, at the surface, or at intermediate 
points. It is an omnivorous and extremely voracious feeder, consuming 
all marine animals of suitable size. Favorite articles are bivalve 
mollusks, crabs, lobsters, starfish, and fish. Among the fish consumed 
in large quantities are capelin, lant, herring, alewives, menhaden, 
mackerel, and haddock, although many others are also eaten. The 
abundance and movements of such fish have an important relation to 
the presence and abundance of cod in a given region. 

WEIGHT AND GROWTH OF COD. 

The largest cod recorded from New England waters weighed 211^ 
pounds and was over 6 feet long; it was taken on a trawl off the 
northern Massachusetts coast in May, 1895. - The capture of a. number 
weighing from 100 to 175 pounds could be cited, but those exceeding 100 
pounds in weight are by no means common, and even 75-pound cod are 
not numerous. The average weight of the large-size cod caught in the 
shore waters of New England is about 35 pounds; on Georges Bank, 
25 pounds; on the Grand Banks and other eastern grounds, 20 pounds; 
the average weight of the small-size fish caught on all these grounds is 
about 12 pounds. 

Observations in Massachusetts of the rate of growth of the cocl sbow 
that those 1£ to 3 inches long are about 6 months old; those 9 to 13 
inches long, and weighing 7 or 8 ounces, are 1 J years old ; those 18 inches 
long, and weighing 2 to 2J pounds, are 2i years old; and those about 22 
inches long, and having a weight of 4 to 5 pounds, are 3£ years old. 



MANUAL OF FISH-CULTURE. 195 

SPAWNING. 

The principal spawning time of the cod on the New England coast 
is winter, but the season begins as early as November and continues 
until April. Spawning fish are occasionally caught from October until 
May. The spawning period for an individual fish is greatly prolonged, 
and probably covers six or eight weeks, only a small percentage of the 
eggs maturing at one time. The male and female cod may attain 
sexual maturity when weighing only 3^ or 4 pounds. The ages of 
normal fish having these weights are supposed to be three to four 
years. 

When impelled by the spawning instinct, the cod seek the shoal 
waters of the coast or banks in schools consisting of both sexes. The 
female is less active than the male at this period, and probably rests 
quietly on the bottom while discharging the eggs. There is no evidence 
to show that the sexes are paired or in close proximity during the act 
of spawning. On the contrary, it seems likely that fertilization is 
generally accomplished by accidental contact of the sexual products 
as they are swept about by the elements, having risen to or near the 
surface as soon as extruded. 

The cod is one of the most prolific fishes. The ovaries of a 21-pound 
fish have been computed to contain 2,700,000 eggs, and a 75-pound cod 
has been estimated to have 9,100,000 eggs, these figures being deduced 
by careful weighing or measuring of a known number of eggs. The 
egg is from -^ to py inch in diameter, the smallest fishes having the 
smallest eggs; the average size may be taken as -^ inch. The approxi- 
mate number in a fluid quart is 337,000. 

The destruction of cod eggs in nature is necessarily large. The 
principal loss is probably through failure of impregnation, the eggs 
losing their ability to become fertilized and the milt its vitality very 
soon after being thrown from the fish. Incalculable numbers are thrown 
on the shore by the waves and there die. Cod eggs are also destroyed 
by numerous animals, including fish, birds, and invertebrates. 

COMMERCIAL IMPORTANCE AND FOOD VALUE. 

The cod is one of the most valuable of all food-fishes, and in the 
United States ranks as the most prominent commercial fish. In the 
matter of persons engaged, vessels employed, capital invested, and 
value of catch, the taking of cod in the United States is more extensive 
than any other fishery for fish proper.* The number of vessels which 
fish wholly for cod or take cod in noteworthy quantities, together with 
other "ground fish," is not less than 600, of over 25,000 net tons burden, 
carrying about 7,000 men, and with a value of $3,000,000, besides which 
there- are very large fisheries carried on from boats and small vessels 
of less than 5 tons burden. The approximate annual value of the cod 

* The oyster fishery is the most important hranch of the fishing industry of the 
United States. 



196 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 

catch in recent years is about $3,000,000, a sum representing the first 
value of the fish. The weight of the fish as landed from the vessels 
(fresh, split, and salted) is about 100,000,000 pounds. 

The cod fishery is prosecuted in all the coastal States from Maine 
to New Jersey, being most important in Massachusetts and Maine. 
Gloucester and Boston are the principal fishing centers. On the 
Pacific coast there is an important fishery in Alaska, carried on by San 
Francisco vessels. 

Cod are taken with hand and trawl lines, baited with fish, squid, etc., 
and fished from small boats or the vessel's deck. The principal grounds 
in the Atlantic are the famous "banks" — Grand, Georges, Western, 
Quereau, etc.; on the Pacific coast the Shumagin Islands are the chief 
grounds. Small quantities are taken in traps at places on the New 
England shore. 

ARTIFICIAL PROPAGATION. 

The cod is propagated artificially on a more extensive scale than 
any other marine fish. Artificial hatching was first undertaken at 
Gloucester, Massachusetts, in the winter of 1878-79, and has since been 
regularly prosecuted on an increasingly large scale at both Gloucester 
and Woods Hole. Up to and including the season of 1896-97, the 
number of cod fry liberated by the Commission on the east coast was 
449,764,000. The output of fry in the last-named year was 98,000,000. 
The unmistakable economic results which have attended these efforts 
warrant all the time and money devoted to them and justify the greatest 
possible expansion of the work. 

COLLECTING- EGGS ON THE FISHING-GROUNDS. 

The following methods are pursued in collecting cod eggs for the 
United States Fish Commission station at Gloucester. 

As cod are abundant in Ipswich Bay during the winter, vessels from 
Gloucester, varying in size from 10 to 70 tons, engage in fishing there, 
starting from Kittery Point, Maine, or Portsmouth, New Hampshire, 
where they market their catch, secure bait, and obtain supplies. At 
the beginning of the cod season (which usually opens from the middle 
to the last of November) arrangements for the board of the men, dory 
and building hire, transportation of eggs, etc., are made with persons 
at Kittery Point and permission to place spawn-takers aboard the 
fishing vessels is obtained, with the understanding that they will be 
allowed to take eggs from the fish secured, that they be given the 
freedom of the vessel in order to properly care for the eggs, and that 
no charges be made against the Commission except that 25 cents be 
paid for each meal furnished the spawn-takers. After these arrange- 
ments are made the men are directed to board such of the fleet as are 
at the time meeting with the best fishing, but as the fish are not of 
uniform abundauce in the bay it is necessary to keep a vigilant watch 
on each vessel's catch as it is landed, daily, to know where to place 
the spawn-takers to the best advantage. 



Report U. S. F. C. 1897. (To face page 196.) 



Plate 53 




MANUAL OF FISH-CULTURE. 197 

A spawn-taker's outfit consists of a water bucket or pail, a dipper, a 
siphon, a thermometer, and a tin spawn-kettle about 2 feet long, 1 foot 
wide, and 8 to 9 inches deep; the kettle has a cover and handle. 

When new spawn-takers are employed they are instructed in the 
work and sent out in vessels with the experienced men to familiarize 
themselves with the methods. The spawn-takers ordinarily leave their 
boarding-places at 1 o'clock in the morning (though the time varies 
somewhat, according to the weather) and join the boats anchored in the 
harbor of Kittery or at Portsmouth. During moderate weather the men 
frequently go aboard before midnight, as the vessels must sail when 
the tide is favorable, to avoid getting becalmed or meeting a head tide, 
either of which might prevent them from reaching the fishing-grounds 
in good season. 

After joining the vessels, the spawn-takers usually assist the fisher- 
men in getting under way, managing the ship, etc., and on reaching the 
place where the nets or trawls are set — usually 6 to 10 miles distant — 
the spawn-takers help the crews in hoisting out and dropping the dories 
on the gear as each buoy is reached, the men remaining on the vessel's 
deck with the captain while the fishermen are hauling or under-running 
their gear, and until they return to the vessel with the fish. 

As soon as the dories begin to arrive with fish, the work of the spawn- 
taker begins. As the fish are pitched aboard, the spawn-taker stands 
ready to examine each one and select those that may contain ripe eggs 
or milt. As the dories are usually picked up in the same order in which 
they are dropped, there is opportunity to strip the fish without much 
hurry, but sometimes several are picked up in a short space of time, 
and if a large quantity of fish is landed the catch remains on deck 
until the spawn-taker can overhaul it. In bad weather, however, when 
the fish would be in danger of being washed away, they are put in bins 
on deck and can be pitched from one bin to another by the spawn- 
taker as the condition of each is determined. Usually one of the crew 
assists in this work and often renders valuable assistance. Great care 
is taken not to get any green or dead eggs with the good ones and to 
keep the eggs as free from foreign matter as possible; but in rough 
weather, when the vessel is pitching or rolling heavily, vigilance in 
these respects is necessarily somewhat relaxed. 

The spawn-taker seizes the fish by the tail, places the head under the 
left arm, if it is not too large, leaving the right arm free for stripping 
the fish, which is done in the usual way. Only live fish or fish recently 
dead are used. 

The eggs are first taken in a common pail, the inside of which has 
been moistened with water. Then a sufficient quantity of milt to 
fertilize the eggs.is added and thoroughly mixed with them and allowed 
to remain from 10 to 20 minutes, or longer, after which water is added 
and the eggs are carefully cleaned by siphoning off the old water 
and putting in fresh water until all the slime and milt are drawn from 
the pail. The good eggs, which rise to the surface of the water, are 



198 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 

then transferred to the spawn-kettle containing clean water and the 
poor or dead eggs are thrown away. 

All the eggs obtained on a given vessel are kept in the kettle until 
the receiving-house on shore is reached, the water on the eggs being 
changed at intervals during the passage in ; and to keep the tempera- 
ture uniform, the eggs -are shifted from one part of the vessel to 
another, according to conditions. Sometimes, when the sea is very 
choppy or rough, the pail can not safely be used, as the eggs will spill 
out, and they are then stripped directly in the spawn-kettle and cleaned 
as well as possible. 

It was formerly the practice to take cod eggs in a small quantity of 
water, but during the season of 1896-97 it was determined to test the 
relative efficacy of the so-called wet and dry methods of fertilization. 
Some of the spawn-takers were instructed to employ the dry method 
and others the wet method. The experiments show that when eggs 
were taken by the dry method a much larger percentage was fertilized 
than when taken in water. Eggs from fish caught on trawl lines inva- 
riably yield a larger percentage of fry than those from fish caught in 
nets, although fine eggs are frequently obtained from net fish. The 
explanation seems to be that fish caught in nets soon become entangled 
and are either drowned, or nearly so, shortly after being meshed; they 
struggle a great deal more than fish on trawls and the greater part of 
them are dead when taken into the boats, many of them being scaled, 
which indicates severe exertion in trying to escape. Trawl fisb, on the 
other hand, are almost always alive and active when taken from the 
water, and very few fish without scales are found unless the gear has 
been out a long time or has been set during a heavy storm, when, of 
course, many of the fish will be dead. 

Better results are obtained from eggs taken when the weather is 
fairly cold than when it is warm, as when the temperature is high it is 
difficult for spawn-takers to keep the water containing the eggs at a 
safe temperature, and before the egg house on shore is reached there is 
almost always a heavy loss. When the weather is too cold for eggs to 
be kept on the vessel's deck the spawn- takers put them below the deck, 
where the temperature will be suitable. 

Many difficulties and much exposure are encountered by the men 
who collect cod eggs on the fishing vessels, and during severely cold 
and windy weather, when the deck is covered with ice and the fish 
freeze stiff in the dories before they reach the vessel, it is practically 
impossible to get good eggs. During boisterous weather, when the 
fleet succeeds in hauling the gear only once or twice a week, the greater 
part of the catch is generally dead when taken. A spawn-taker often 
secures a good lot of eggs and can find no ripe milt fish, but in this 
event he will, if the weather permits,' visit the nearest vessel in quest 
of milt. Sometimes there is a school of milt fish in the bay and very 
few female fish, and a vessel may catch several thousand pounds of cod 
day after day without finding ripe spawn in any of them, while another 



Report U. S F, C. 1 897. (To face page 1 98.) 



Plate 54. 




MANUAL OF FISH-CULTURE. 199 

vessel, fishing only a short distance away and not catching many fish, 
will get a comparatively large number of spawners. 

The spawn-takers are instructed not to take eggs from fish that have 
died on trawls or in nets, although fine lots of eggs are often taken from 
iish that die in the dories before they reach the vessel, showing that the 
eggs do not die immediately after the fish expire. The vitality of the 
eggs after the death of the fish varies in different cases and depends on 
the conditions of the eggs and the fish at the time the fish are caught, 
the state of the weather, etc. An experienced spawn-taker can almost 
always distinguish readily between good and poor eggs, although it is 
not always possible to determine whether or not a given lot of eggs will 
live. As the weather and the nature of the school of fish in the bay 
regulate the collection of eggs, the results of a season's work can not be 
estimated in advance. It has been observed that roe fish are found in 
largest numbers previous to an easterly storm and when the wind is 
from the south or west. During heavy westerly winds cod appear to 
approach quite close to the beach, and when the wind blows from the 
eastward and the sea begins to rise, they leave for deeper water. 

When fishermen are hauling their nets and trawls, they frequently 
notice spawn being emitted from fish when they are landed in the 
dories. Such fish are laid away on their backs in the stern of the boat 
and when the vessel is reached are carefully passed to the spawn-taker, 
many eggs that would otherwise be lost being thus saved. 

When the price of fish is low at Portsmouth or the wind is unfavor- 
able for making that harbor, some of the fleet go to Rockport to sell 
their fish, and should spawn-takers be on such vessels they immediately 
take their eggs to Gloucester when the vessels arrive in Bockport. 

Usually the fishing vessels return to Kittery Point between 1 o'clock 
and 10 o'clock p. m. Immediately on landing, the spawn-takers carry 
their collections to the egg-house on shore, where the spawn is carefully 
examined, cleaned, packed, and shipped to Gloucester by first train. 
In shipping eggs large fruit jars are used. About 350,000 eggs are put 
in each jar, the jar is filled with water, the top is securely fastened, 
and the jar is placed horizontally in a large iron kettle made especially 
for the purpose and holding five jars. The jars are wrapped in burlap 
before they are put in the kettles to prevent them from breaking, and 
when necessary, snow or ice is put in each end of the kettles to keep 
the temperature uniform during transit, but it is not allowed to come 
in direct contact with the jars. 

A messenger usually accompanies the eggs and gives them constant 
attention until they are delivered at the station. The snow or ice is 
removed from the kettles, if the temperature falls too low, and replaced, 
if necessary, the messenger making frequent use of a thermometer. 

In preparing eggs for shipment without messenger, they are first 
cleaned carefully by drawing off all dead eggs or dirt, then put in large 
fruit jars in the same manner as when they are shipped to Gloucester, 
and the jars are packed horizontally in large wooden cases holding nine 



200 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 

jars each. Kockweed or moss, together with ice or snow, is used in 
packing - them, the former being placed around the jars and the latter 
put in the bottom, sides, and top of the case to keep the eggs cool. 
Successful shipments are often made by express. 

Some difficulty has been experienced in keeping large lots of eggs 
over night at Kittery Point, as the facilities are insufficient for chang- 
ing water or for spreading the eggs out to overcome the injurious effects 
of prolonged crowding; but when it is necessary to so retain them, they 
are put in McDonald jars in which the water is changed as often as the 
supply will permit. As the water in the harbor is partly fresh and 
unfit for this purpose, it is necessary for spawn-takers to bring in a 
supply from the open bay in large transportation cans. 

CAPTURING AND PENNING BROOD COD. 

Practically all of the cod fry hatched at Woods Hole prior to 1896 
represented eggs taken from penned fish. Some of the cod collected 
for breeders are caught by the crew of the Fish Commission schooner 
Grampus and some are purchased from commercial fishermen. Two 
or more smacks usually engage in fishing for the station during the 
collecting season, which is from about October 1 to November 30. The 
grounds resorted to are east of Nantucket and around Block Island. 
The fish are taken with hand lines fished from the deck while the vessel 
is drifting, in water from 10 to 40 fathoms deep. Those taken in the 
shoaler water are preferable to those coming from deep water, as the 
change to the shallow cars in which they are held at the station is less 
pronounced. Great care is exercised in catching the fish, for when 
hastily hauled up from deep water they are very liable to be "poke- 
blown," that is, they have their stomachs turned inside out through the 
mouth. When drawn in with moderate speed, they become adapted to 
the gradually diminishiDg pressure and do not suffer injury. It is also 
important in unhooking the fish not to injure its moutli any more than 
is absolutely necessary, as the wound caused by the hook frequently 
spreads and forms a large sore and eventually kills the fish. All the 
vessels which collect cod for the station are provided with wells in which 
the fish are placed and held while in transit. 

When a vessel arrives at the station with cod, the fish are immedi- 
ately transferred with dip nets from the well to live-cars 16 feet long, 
6 feet wide, and 5 feet deep, which are constructed of wood and divided 
into two compartments by a crosswise partition. As the fish obtained 
from smacks are paid for by the pound, it is customary to weigh about 
10 per cent of each load and estimate the total weight by the average 
of those weighed. While being weighed, the cod are also counted, 
about 500 being put in each car. The cars are moored in the middle 
of a pool or basin protected on all sides by a wharf, which breaks the 
force of the sea in stormy weather and affords a sheltered place for 
handling the fish and taking the eggs. 

Cod take little or no food when spawning. The impounded brood 
fish are often tempted with fresh fish and with fresh and salted clams, 



Report U. S. F C. 1697. (To face page 2C0.) 



Plate 55. 




MANUAL OF FISH-CULTURE. 201 

but they can rarely be induced to eat. A certain percentage of the 
penned fish die and are removed at once from the cars. The develop- 
ment of the sexual organs is noted when the dead fish are taken out. 
Fish about ready to spawn are placed in a separate car and carefully 
watched. They are examined two or three times a week and any ripe 
eggs are taken. 

In taking and fertilizing the eggs of brood cod the same general 
methods are followed as are adopted on the fishing vessels in Ipswich 
Bay. The spawn-taker grasps the ripe fish near the tail with his left 
hand and holds the fish's head either between his body and left arm or 
between his thighs, using his right hand to strip the fish. The eggs 
are usually taken in a bucket. Both the dry and wet methods of fertil- 
ization are used at Woods Hole. Usually about 80 per cent of the eggs 
taken are fertilized. Unlike many other fishes artificially propagated, 
the cod does not yield all of its eggs at one time. After expressing all 
the eggs possible from a given fish, it is returned to the live-car, and in 
a few days will have matured more eggs, which are then taken. When 
the ovaries have discharged all their eggs, the fish is released. 

In recent years from 1,600 to 9,000 cod have been penned annually 
in the protected basin at Woods Hole. Only from one-ninth to one- 
third of these, according to the season, yield good eggs. 

CHARACTERISTICS OF COD EGGS. 

God eggs are nearly transparent, and float at the surface of the water 
when first taken. They vary in color from a pale green to a deep red, 
those having the green color being the best. Good results are seldom 
obtained from the red eggs, and those of a deep red color almost invari- 
ably die in three or four days after being received. Unless the density 
of the water is low, the eggs normally float during the entire hatching 
period. However, it frequently happens that, owing probably to the 
accumulation of sediment, the eggs gradually sink during the last third 
of the incubation period, and finally mass together on the bottom of the 
hatching-box; here they would quickly smother but for the current. 

Floating eggs are not necessarily good ones, for unfertilized and 
injured eggs usually float 18 to 36 hours before going to the bottom. 
Unfertilized eggs may be readily detected, as they have no disc which 
marks fertilization and have a milky appearance. Tk«e dead eggs 
quickly sink, and are easily distinguished from the sound eggs by a 
white spot in the center. 

Eggs received at the hatchery are transferred from the vessels in 
which they came to Chester jars partly filled with water, and in 10 
or 15 minutes they rise to the surface in a dense mass. The eggs are 
put in each jar to the depth of an inch, a quantity representing approx- 
imately 379,000 eggs. If the hatchery is full, about a fifth more eggs 
may be put in a box, the maximum number that may be safely carried 
being 450,000. The first measurements are carefully made, as they form 
the basis for subsequent estimates. As soon as the eggs are measured 
they are transferred to the hatching-boxes with dippers. 



202 



REPORT OF COMMISSIONER OF FISH AND FISHERIES. 



THE APPARATUS USED IN HATCHING CQD. 

The apparatus and methods employed in cod-culture are the out- 
growth of long" experience and study and have as their special features 
the closest possible simulation of natural conditions. The apparatus 
now in general use is the so-called McDonald or automatic tidal bos. 
The boxes are constructed in series of 12 or less, the number depend- 



PLAN. 



O 



O 




r 




Section through fl-B 





Diagram of Tidal Cod Hatchmg-Box. 



A-B Points where cross-section is taken. 
a, siphon. 

c, partitions forming upper pockets. 

d, partition forming space at upper end of 

compartment. 



e, partition forming space at lower end of 

compartment. 
/, glass gate. 
g, slot between adjoining compartments. 



ing on the size of the hatching-room, the arrangement of the hatching- 
tables, or other conditions. The Gloucester hatchery has 8 tables of 
9 boxes each, and Woods Hole 14 tables of 12 each. At Gloucester 
25,000,000 eggs can be hatched at one time, and at Woods Hole 
65,000,000. For a wooden framework to accommodate 9 boxes such 
as are used at Gloucester the outside dimensions are: Length, 10 



Report U. S. F. C. 1897. (To face page 202.) 



Plate 56. 




Mcdonald tidal boxes, used for hatching cod and flatfish. 



MANUAL OF FISH-CULTURE. 203 

feet; width, 3 feet 8 inches; depth, 11 inches. The table or trough is 
constructed of 2-inch lumber and raised to a convenient height by 
short, stout legs. The table is divided into 9 water tight compart- 
ments by means of crosswise partitions of 1^-inch plank. 

At Woods Hole the dimensions of the troughs containing 12 boxes 
are as follows: Length over all, 13 feet; width, 2 feet 7 inches; depth, 
12 inches. The plank is 1£ inches thick. The bottom of the trough is 
2£ feet above the floor. The compartments are separated by 1^-inch 
partitions and are 22 inches long, 12 inches wide, and lOf or 11 
inches deep. 

Two inches from each end of each compartment there is a 1-inch 
wood partition. The partition d at the supply or upper end of the 
compartment extends with its middle portion to the bottom of the 
trough, while the two sides extend only to within 1£ inches of the bot- 
tom. The partition e, at the discharge or lower end of the compart- 
ment, extends its full length to within 1£ inches of the bottom of the 
trough. Between the two partitions d and e in each compartment there 
is snugly fitted a movable box in which the eggs are placed. This 
box, which is constructed of £-inch plank, is 9 to 9£ inches deep in the 
center, but only 8 inches deep at the corners, the bottom sloping 
upward toward the sides and ends of the box and being covered with 
linen scrim. A wooden strip at the bottom, £ inch thick and conform- 
ing to the shape of the bottom of the box, extends the length of the box. 
The box rests on cleats in the corners of the compartments which keep 
the center of the box 1J inches above the bottom of the trough. 

The space at the supply end of each compartment is divided into 
three pockets by 1-inch wood partitions. The middle pocket connects 
with the main compartment by means of a small hole (^ to -^ inch) 
through the center of the partition and end of the box immediately 
above the lengthwise strip, and the two lateral pockets connect by a 
space at the bottom with the main compartment. 

At Woods Hole the water used in hatching is pumped from the 
harbor to two tanks of about 18,000 gallons joint capacity. The water 
is led to the hatching-room through a 4-inch wooden pipe and is sup- 
plied to the hatching apparatus through a 2£-inch hard-rubber pipe 
which branches from the main pipe and runs directly over each row of 
tables. At Gloucester the main supply-pipe is of hard rubber, 3 inches 
in diameter; this leads from a tank of 15,000 gallons capacity, the 
bottom of which is about 6 feet above the level of the troughs. A small 
soft-rubber tube, provided with a rubber pet-cock, carries the water to 
the middle pocket at the back of each box. As the pocket is always 
full of water when the boxes are in operation, a considerable amount 
of water goes through the small hole with much force, creating a strong 
current in the box and keeping the eggs in constant rotary motion. 
This current is one of the principal features of the apparatus. 

Much more water enters the middle pocket than can pass through 
the small hole into the box, and the surplus flows over the sides and 



204 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 

enters the main compartment from below, coming up through the scrim- 
covered bottom into the movable box. 

The partition forming the pocket at the lower or front end of the box 
only extends to within 1£ inches of the bottom, leaving a space 
through which the water runs from the compartment. In the bottom 
of the pocket there is an opening in which the vertical waste-pipe fits. 
This pipe is brass, J inch in diameter and 10 or 11 inches long; the top 
of the pipe is 7 inches above the bottom of the table. The waste-pipes 
from the different boxes discharge into a trough which carries the water 
from the building. 

A particularly important part, and the one which gives the name 
"tidal box" to the apparatus, is used in conjunction with the waste- 
pipe. This is a brass siphon-cap, which fits over the upper end of the 
waste pipe. The cap is a tube, closed at the top, 9 inches long and 1 J 
inches in diameter. It is kept at any desired height on the waste-pipe 
by wire springs in the cap or by other means. 

By virtue of the siphon attachment the water in each box rises to 
the height of the top of the waste-pipe and begins to run over. This 
partly exhausts the air in the cap, more water rushes in, and the pipe 
becomes filled with water ; then the siphon begins to act and takes off 
the water to a level of the bottom of the siphon-cap. Usually the cap 
is pushed about half down the waste-tube, although the height of the 
water in the box after the discharge of the siphon is regulated by the 
manner in which the eggs are working. About 7 minutes are required 
for the water to be drawn down and the box to again fill, and approxi- 
mately two-fifths of the water is taken off at each discharge. By this 
arrangement the water in the* boxes is constantly rising and falling 
automatically; the movements of the waves are thus simulated, the 
eggs are kept in constant circulation, and fresh water is continually 
entering the boxes. 

The Chester box was generally used in cod-culture up to a com- 
paratively recent date, and is still occasionally employed in marine 
fish-cultural operations. The general object of its construction is the 
production of an automatic rise and fall of water, as in the McDonald 
box, although it differs from the latter in some essential particulars. 
It consists of a box of variable dimensions in which jars are placed for 
the reception of the eggs. A convenient size of box is 7£ feet long, 2 
feet wide, and 2£ feet deep. From 4 to 8 large glass jars are arranged 
on wooden supports 7 or 8 inches above the bottom of the trough. 
Smaller boxes, to accommodate only 2 or 4 jars, are also used. The jars 
are about 9 inches in diameter and are of two heights — 9 inches and 17 
or 18 inches ; they have straight sides and a flat bottom with a central 
half -inch hole. 

The jar is placed in the box in an inverted position, with its bottom 
above the level of the top of the trough. The sea water supplying the 
trough enters the compartment at one end of the trough and escapes 



Report U. S. F. C. 1897. (To face page 204. 



Plate 57. 




CHESTER BOXES. 



MANUAL OF FISH -CULTURE. 205 

by means of a siphon in the other compartment, running through a hole 
several inches below the top of the trough. The trough fills with water 
up to a level with the hole, when the siphon begins to act and takes off 
the water more rapidly than it enters, to a level with the inner end of 
the siphon, the fall being 4 to 5 inches. Air then enters the siphon, 
and it ceases to act until the water has again risen to the height of the 
discharge hole. The water thus rises and falls in the jars automatically, 
the interval between the successive discharges being regulated by the 
length of the inner arm of the siphon, the size of the tube, and amount 
of water supplied. 

After the eggs are introduced into the jars a piece of cheese-cloth or 
linen scrim is placed over the top, and fastened by means of rubber 
bands. The jar is then inverted and placed on the wooden supports 
provided for the purpose, and the plug in the bottom removed to allow 
the escape of the air and the rise and fall of water. The number of 
eggs per jar is about 190,000 or 200,000. 

DEVELOPMENT OF THE EGO. 

The development of the cod egg is greatly influenced by the water 
temperature, which fluctuates from day to day and makes it difficult to 
state exactly when the eggs will hatch. With a high temperature the 
advancement of the egg through the different stages proceeds rapidly 
and can readily be appreciated with the unaided eye, while with a low 
temperature the development is slow and may be greatly prolonged 
by very cold water. With a mean temperature of 47° cod eggs begin 
to hatch in 11 days, although 2 or 3 additional days are usually nec- 
essary for all the eggs of a given lot to hatch. At 43° the time is 14 
or 15 days, and at 38° it is 20 to 23 days. The best results are obtained 
when the temperature ranges from 41° to 47°. The hatching proceeds 
satisfactorily with the water at 38°, but with a lower temperature 
the incubation period is so long that the fry are very weak. On the 
natural spawning-grounds the water seldom gets below 38°, while at 
the stations after January 1 the water used for hatching rarely gets 
as warm as 37°, and often is as low as 31° ; from the middle of January 
to the latter part of February it remains at about 32°. Since it is 
impossible to do even fair work when the water gets below 35°, it has 
been the practice to warm the water by passing it through a coil of pipe 
contained in a tank of warm water or by introducing steam directly 
into the water pipe whenever the hatchery water gets below 37°. 

The water being at 47°, during the first 4 days the egg passes 
through the different stages of segmentation; at the end of that time 
the germinal area begins to assume the general form of a fish; and by 
the ninth day the fish is quite well formed, and may be readily seen 
with the naked eye. By the tenth day the embryo shows signs of life, 
and under the microscope the heart may be seen to beat, 



206 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 

Following is a table showing the approximate time required for cod 
eggs to hatch, with the water at the stated mean temperatures : 



Mean water tem- 
perature. 


No. of 

days. 

50 
40 
35 
31 
28 
25 


Mean water tem- 
perature. 


No. of 
days. 


Mean water tem- 
perature. 


No. of 
days. ' 


31° F 

32° F 

33° F 


37° F 


1 
23 
21 
19 
17 
16 
15 


43° F 


14 
13 
12 
11 
10 or 11 


38° F 

39° F 


44° F 


45° F 


34° b" 


40° F 


46° F 


35° F.. .... 


41° F 

490 jp 


47° F 


36° F 









Moderately clear water is essential to the healthy development of 
the fry. If much sediment is present it collects on the eggs and acts 
very injuriously, often killing them. Sometimes eggs become so coated 
with sediment that the fry appear to be unable to burst the shell; 
some lots of eggs thus affected have been known to retain fry fully two 
weeks beyond the normal period of incubation. 

With eggs carefully taken and fertilized, and clear water of a 
temperature from 41° to 47° F., it is possible to hatch from 70 to 85 
per cent of the eggs, but when the temperature gets below 38° the 
percentage of fry hatched is only from 25 to 50, and the average for the 
season is thus greatly reduced. The number of fry hatched is deter- 
mined by deducting the losses shown on the hatching-cards from the 
number of eggs originally in the box. One liquid ounce is estimated 
to contain 10,524 eggs. 

CLEANING THE EGGS. 

Owing to the accumulation of sediment and other foreign matters in 
the hatching-boxes, it is necessary to clean the eggs daily, running the 
sound eggs from one box to another through a slot, the dead eggs 
being left behind. The slots in the partitions dividing the hatching 
compartments correspond with similar slots in the boxes ; they are 3 
to 3^ inches long and 1£ inches deep, and are placed 3 inches from the 
front of the compartments. To begin the cleaning of a given row of 
boxes, a glass slip is fitted into the slot between the second and third 
boxes, the first box being left empty for the purpose of receiving the 
cleaned eggs from the second box. A wooden plug is then put in the 
current hole at the back of the second box, and the siphon cap is 
removed from the waste-pipe; this allows the box to fill with water, 
and the eggs, undisturbed by the current, rise to the surface. The 
water is allowed to enter the first box and to gradually fill it to the 
level of the waste-pipe, and is then turned off. A plug is next put in 
the waste-pipe of the box containing the eggs; the water rises till it 
reaches the slot, and then runs over into the first box, carrying the good 
eggs with it, while the dead eggs remain in the box. The regular water 
circulation is then established in the first box. 

The inner box from which the good eggs have been removed is taken 
out and the remaining eggs are washed into one end and poured into 



MANUAL OF FISH-CULTURE. 207 

a glass graduate. The dead eggs quickly sink and the quantity, in 
ounces, is noted on a card attached to each box. If there are any good 
eggs in the glass they are saved; the spoiled eggs are thrown into the 
waste- trough. Both the inner box and the trough in which it rests are 
thoroughly washed and sponged after each change. 

When the inner box is replaced it is made ready for the eggs to be 
transferred from the third box, and the same method is pursued until 
all the boxes have been cleaned. Eggs recently taken, being on the 
surface, run over very quickly, 5 or 10 minutes usually sufficing for 
the transfer of a box of 400,000 eggs; but when eggs become heavier, 
as a result of development, the cleaning takes much longer, as it is then 
necessary to run them into the lower part of the box (as in removing 
dead eggs) and to dip them out, care being taken to keep the lower 
end of the box in the water while manipulating them. As the loss of 
eggs has ceased by the time they reach this stage, everything in the 
box may be dipped over, and with care no damage is done the eggs. 

THE FRY. 

When the fry first hatch they are much curved in shape and show 
but little vigor. If the water is comparatively warm they rapidly 
straighten out and become stronger. At this stage they float at the sur- 
face, except when forced about by the current. As they get older they 
frequent the upper water less and if kept in the boxes till the mouth 
begins to functionate most of them remain on or near the bottom. 

As soon as the first fry in a given box make their appearance the 
eggs are all rum-over for the last time. As the fry are comparatively 
delicate they are handled as little as possible and with great care. 

The fry are planted as soon as practicable. If all the eggs of a given 
lot have not hatched it is better to plant them with the fry rather than 
hold the latter until incubation is complete, for the boxes soon become 
foul from the accumulation of eggshells and the eggs will haitcti in a 
very short time, especially as the water on the spawning-grounds is 
usually 3 or 4 degrees warmer than the water in the hatchery. 

When the fry are to be removed from the boxes, preparatory to plant- 
ing, a plug is put in the current hole at the back of the box, and in a 
short time most of them will come to the surface. They are then dipped 
ouit and put in transportation cans. About 200,000 fry may be safely 
carried in a 10-gallon can. Deposits are usually made on the natural 
spawning- grounds. 



Report U. S. F. C, 1897. (To face page 209.) 



Plate 58. 






¥ 




■ ■ 

» " \' J ' >.'■'■■■■■.■ ■ 




THE COMMON MACKEREL. 



DESCRIPTION, SIZE, ETC. 

The genus Scomber, of which the common mackerel (S. scombrus) is 
the leading representative, is distinguished from related genera of 
scombroid fishes of the Atlantic coast (Auxis, the frigate mackerels; 
Gymnosarda, the little tunnies; Thunnus, the great tunnies; Sarda, the 
bonitos, and Scomberomorus, the Spanish mackerels and kingfish) by 
the small size of the species, by the absence of a median keel on each 
side of the caudal peduncle, by a short spinous dorsal fin having 9 to 
12 spines, by the pattern of coloration, and by a number of other 
characters. 

The body of the mackerel is fusiform and but little compressed later- 
ally. The standard length is 3£ times the depth. The caudal peduncle 
is slender, with a small keel on either side. One-third of the total 
length without tail consists of the head. The eye is rather small, its 
diameter being only one-fifth the length of. the head. The mouth is 
large and armed with a row of small slender teeth in each jaw. There 
are two dorsal fins, the anterior containing 11 spines and the posterior 
12 rays, following which are 5 finlets; the formula of the anal fin is 1 
spine, 11 rays, and 5 finlets. The scales are very small, numbering 
several hundred along the lateral line. The color is dark blue above 
and white below. About 35 dark wavy vertical streaks mark the back. 

The common mackerel closely resembles the other species of the same 
genes found on both the Atlantic and Pacific coasts, namely, the bull's- 
eye, chub, or thimble-eye mackerel (S. colias), but is separated from it 
by the absence of the air-bladder, more dorsal spines, smaller eye, and 
somewhat different markings. 

The length of the full-grown mackerel is 17 or 18 inches, but fish a 
little over 20 inches long, and weighing upward of 3^ or 4 pounds, are 
occasionally taken. The average length of the market catch is about 
12 inches. Such a fish weighs from three-fourths of a pound to a pound. 

Small mackerel are known among the fishermen by several names, 
such as u spikes," "blinkers," and " tinkers." Spikes are the smallest 
caught by the commercial fishermen; they are 5 or 6 inches long and 
are 5 to 7 months old. Tinkers are under 9 inches in length and are 
supposed to be about two years old. Blinkers are intermediate in size 
and age. Maturity is probably attained in the fourth year. 

DISTRIBUTION, MOVEMENTS, ABUNDANCE, AND SPAWNING:. 

This species inhabits the North Atlantic Ocean. On the American 
coast its range is from Oape Hatteras to the Straits of Belle Isle. On 
the European coast the fish is found from northern Norway, in latitude 

F. Q r R. 1897 14 g09 



210 REPORT OF COMMISSIONER OP FISH AND FISHERIES. 

71°, to the Mediterranean and Adriatic. It is not recorded from the 
West Indies, Bermudas, Gulf of Mexico, South America, or Africa. 

On the east coast of North America mackerel first appear in the 
spring off Cape Hatteras and subsequently reach the shores of the 
Middle and New England States and the British. possessions, migrating 
in from the sea from a southerly or southeasterly direction. Certain 
bodies of fish seek the New England shore, while others first strike the 
shore of Nova Scotia and follow it into the Gulf of St. Lawrence. 
They leave the coast in the same way in fall and early winter. 

The mackerel is a wandering fish. Its movements when in the coast 
waters are undoubtedly regulated by external causes not yet clearly 
understood, but food, temperature of water, and reproduction are potent 
factors. 

The mackerel is one of the most abundant fishes found on the Atlan- 
tic coast. It goes in schools, often of immense extent. The testimony 
of reliable fishermen relative to the size of schools observed often 
seems incredible; thus one school seen in the South Channel in 1848 
was half a mile wide and at least 20 miles long. Another school noticed 
off Block Island in 1877 was estimated to contain 1,000,000 barrels. The 
schools swim at the surface or at varying depths beneath the surface, 
and present a comparatively broad front. 

From the earliest times, there have been periods of scarcity of mack- 
erel alternating with seasons of abundance. As early as 1670 the 
Colony of Massachusetts enacted laws for the preservation of mackerel. 
Since 1885 there has been the most noteworthy and prolonged scarcity 
of the fish of which there is any record. The New England catch in 
1885 was 330,000 barrels, and in the 8 years ending in 1885 averaged 
309,000 barrels; in 1886 it fell to 80,000 barrels, and in the succeeding 
10 years aggregated only 481,000 barrels; was several times below 
25,000 barrels, and never exceeded 89,000 barrels. The yield in 1896 
was the largest in 9 years. 

The spawning season on the east coast of North America includes 
the months of May, June, and July, June probably being the principal 
month. The spawning-grounds are in rather deep water and extend 
along the entire coast from Long Island to the Gulf of St. Lawrence. 
Most of the bays and sounds of the New England coast are important 
spawning-grounds, as is also the Gulf of St. Lawrence. Prior to 
spawning and for several weeks thereafter the mackerel are lean and 
poor and never make No. 1 fish when salted. 

FOOD AND ENEMIES. 

The mackerel feeds on a large variety of small animals, and is in 
turn eaten by a number of fishes, birds, cetaceans, etc. The relations 
existing between the presence of favorite food and of enemies on one 
hand and of mackerel on the other are fully appreciated by the com- 
mercial fishermen, who are often guided in their search for fish by the 
appearance of mackerel food in abundance or of their well-known 



MANUAL OF FISH-CULTURE. 211 

enemies. The presence of food is frequently shown by flocks of birds, 
especially phalaropes, which are called " mackerel geese." 

The principal food objects of the mackerel are small crustaceans; 
copepods predominate, but shrimps of various kinds, young crabs, etc., 
are also important. One of the surface- swimming copepods, known 
as "red feed," "cayenne," etc., is a very favorite food; when mackerel 
have been feeding^ freely on it, they spoil very quickly after being 
caught, owing to their sides rotting or "burning." Fish constitute a 
rather important part of the mackerel's diet; herring, anchovy, sand 
launce, silversides, menhaden, and many other small fishes are eaten. 

Among fishes, sharks are, perhaps, the most destructive enemies; 
mackerel sharks and dogfish are known to prey on the mackerel, 
driving and scattering the schools. Other fish enemies are bluefish 
and cod. Porpoises and whales are often seen feeding on the mackerel 
schools. Large squids do great damage to small mackerel. Among 
birds, the gannet is especially destructive. 

THE MACKEREL FISHERY. 

The mackerel is one of the best and most valuable food-fishes of the 
Atlantic Ocean. It is the object of important fisheries in Norway, 
Ireland, and Great Britain, and is extensively taken in the United 
States and the British provinces of North America. The fishery is 
prosecuted with vessels using purse seines, gill nets, and lines, much 
the largest part of the catch being taken in seines. In the boat fishery, 
lines and nets are employed. Stationary appliances, such as pound nets, 
trap nets, and weirs, also secure considerable quantities of mackerel. 

In the United States the vessel fishery is carried on chiefly from 
Gloucester, Mass. The vessels sail south in early spring and fall in 
with the fish when they first appear off the coast of the Southern and 
Middle States, the catch being landed fresh in New York and Philadel- 
phia. The fleet next seeks the fish on the southern shore of Nova 
Scotia and follows the school north to the Gulf of St. Lawrence. 
During the summer some of the vessels enter the gulf, but most of 
them cruise on the New England shore, where most of the fall fishing 
is also done. Some of the finest fishing vessels of the United States 
are engaged in this fishery. In recent years the fleet has numbered 
only 150 to 225 sail, but formerly nearly 1,000 vessels were at times 
employed in this branch. 

The shore and boat fishing is carried on from New Jersey to Maine. 
The fish thus caught are as a rule sold in a fresh condition. 

The fishery is much less productive than formerly, and during the 
past ten years has not as. a rule been profitable, although each year a 
few vessels make good catches and yield very satisfactory returns, 
owing to the high price of fish. The local fishing does not supply the 
home demand, and large quantities of fresh and salt mackerel are 
annually imported from Norway, Ireland, and the British provinces, 



212 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 

ARTIFICIAL PROPAGATION. 

The artificial propagation of mackerel was more extensively prose- 
cuted in 1896 tlian in any previous year. The long- continued scarcity 
of mackerel on the Atlantic coast of the United States seemed to 
warrant some efforts on the part of the Government to increase the 
supply by artificial means. The limitations of mackerel culture depend 
on the erratic movements of the fish in a given season or on a given 
part of the coast and the difficulty of securing healthy eggs in large 
quantities from fish taken by the commercial fishermen. During the 
summer of 1896, 24,000,000 mackerel eggs were collected. The work 
was largely experimental and only a small percentage of fry was hatched, 
but the outlook is good for a great expansion of mackerel propagation. 

The egg of the mackerel is one of the smallest dealt with by the fish- 
culturist, being only -^ inch in diameter. Being provided with a large 
oil-globule, it floats at the surface, like the eggs of many other marine 
fishes. Within 48 hours after fertilization it generally begins to sink, 
remains in suspension a short while, and then falls to the bottom, 
where it remains until hatching ensues. 

Owing to the inability to retain mackerel in ponds or live-cars pend- 
ing the ripening of the eggs, as is done with the cod, it is necessary to 
depend for the egg supply on the nets of the fishermen. The eggs 
collected at Woods Hole are secured from fish captured in pound nets 
near Chatham and at other points on the southern Massachusetts coast; 
at Gloucester traps in the vicinity furnish the eggs. As the nets are 
usually hauled only once or twice a day, the fish have often been caught 
for many hours, and the tender eggs have undergone considerable loss 
of vitality; the quality of the eggs seems to have a direct relation to 
the length of time the fish have been in the nets. 

One of the most favorable grounds for collecting mackerel spawn is 
Oasco Bay, on the coast of Maine. Mackerel are taken chiefly in drag 
nets set about 4 o'clock p. m., and hauled from 9 o'clock p m. to day- 
light. Eggs from fish caught in the first hauls of the nets are of much 
better quality than those taken in the last lifts. 

In collecting eggs from pound nets the spawn-takers accompany the 
fishermen when they visit their nets and overhaul the mackerel as they 
are taken into the boats. The collection of eggs from the drag-net 
fishermen requires the spawn-takers to remain on the fishing-grounds 
from early in the afternoon until the next morning. 

There is nothing peculiar in the methods of stripping the fish, mixing 
the eggs and milt, and transferring the eggs from the field to the hatch- 
ery. Although both the wet and the dry methods of fertilization have 
been practiced, the latter apparently gives better results. The average 
number of eggs taken from a fish is probably about 40,000. Three 
mackerel, stripped at Woods Hole in 1893, yielded 434,500 ripe eggs, an 
average of 144,833 eggs. As many as 546,000 eggs have been taken 
from a Impound fish, and the largest fish probably yield fully 1,000,000 



MANUAL OF FISH-CULTURE. 213 

eggs. The largest number of eggs taken from one fish in Casco Bay 
in 1897 was 200,000. 

From the field the fertilized eggs are conveyed to the station in jars, 
as described in the chapter on cod propagation. For short shipments 
they may be transported in buckets or cans. 

Mackerel eggs may be artificially incubated in a variety of ways. In 
1896 three forms of apparatus were employed for comparative purposes. 
These were (1) the McDonald hatching-jar, with the water supplied 
through the long central tube aud discharged through a cheese-cloth 
top; (2) the Chester jar, and (3) the automatic tidal-box; the latter 
gave the best results. 

Owing to the very small size of the eggs, from 200,000 to 225,000 
may be placed in a Chester jar and 450,000 or more in a tidal box 20 
by 11 inches. The eggs are manipulated in about the same way that 
cod eggs are, but, owing to the short period of incubation, require very 
little handling. 

For reasons not yet definitely determined, but apparently connected 
with the condition of the eggs rather than the methods of hatching, 
mackerel ova are liable to exceedingly large mortality during incuba- 
tion. While as many as 75 per cent of certain small lots of eggs have 
produced fry, less than 1 per cent of most of the eggs hatch. 

The period of incubation at a mean water-temperature of 58° is about 
5 days. In 48 hours after impregnation the embryo is discernible, and 
in 68 hours its development is far advanced. The critical period seems 
to be the end of the third day, when a large part of the eggs die. 

The fry are planted within 24 hours of hatching. They are taken 
to the natural spawning-grounds in regular transportation cans and 
liberated below the surface of the water. 



Report U. S. F. C. 1897. (To face page 215.) 



Plate 59. 





THE FLATFISH, OR WINTER FLOUNDER. 



The body of the flatfish (PseudopJeuronectes americanus) is regularly 
elliptical. The eyes and color are on the right side. The upper side 
of the head is covered with imbricated ctenoid scales similar to those of 
the body; the blind side of the head is nearly naked. The teeth are 
close-set, incisor-like, and form a continuous cutting edge; the right side 
of each jaw is toothless. The length of the head is contained 4 times 
in the length of the body and the depth 2f times in the body length. 
The dorsal fin contains 05 rays and the anal fin 48 rays. The lateral 
line, which is nearly straight, has 83 scales. The color above is dark 
rusty-brown, either plain or mottled with darker; the young are olive- 
brown, spotted with reddish; the under parts are white. 

This species has a comparatively small mouth, and feeds chiefly on 
small shells, crabs, and other bottom animals. It is found on sandy, 
muddy, or rocky bottoms, and seems to prefer sheltered coves and 
bays. Its coastwise and bathic movements are limited. It is one of 
the most abundant flounders of the Atlantic coast, being especially 
numerous in southern New England and New York. It ranges as far 
north as Labrador and as far south as the Oarolinas, but is not present 
in noteworthy quantities south of New Jersey. It does not attain a 
large size, the usual length being only 12 to 15 inches and the weight 
about li pounds. Very rarely examples are taken over 20 inches long, 
weighing as much as 5 pounds. 

The winter flounder is exceedingly prolific, over a million eggs being 
laid by a large fish. Along the coast of the southern New England and 
Middle Atlantic States the spawning season is from February to April. 
By August the young fish, having attained a hength of 1 or 2 inches, 
are found in shallow water along sandy shores. The species is obtained 
principally during the winter and spring months, and large quantities 
are sent to the markets, where it sells readily at good prices. The 
flesh is white, firm, and of excellent flavor. Next to the halibut and 
the summer flounder, or plaice (Paralichthys dentatus), this is the most 
important flatfish of the Atlantic coast. 

The winter flounder has been more extensively propagated than any 
other species of Pleuronectidcr, owing to the facility with which its eggs 
are obtained at Woods Hole, where its propagation fills in the time 
between the taking of cod eggs on one hand and of lobster eggs on the 
other, slightly overlapping the ending of the former and the beginning 
of the latter. The work covers that part of the year when the most 

SIS 



216 REPORT OF COMMISSIONER OP FISH AND FISHERIES. 

inclement and changeable weather occurs, and. is necessarily somewhat 
limited in extent by uncontrollable physical and other conditions. 

During the fiscal year 1895-96, the collections of flatfish eggs num- 
bered 11,008,000, which yielded 8,472,000 fry; in, the year 1896-97 
84,591,000 eggs were taken, from which 64,095,000 fry were hatched. 

The flatfish from which eggs are obtained are very plentiful during 
February in the Woods Hole region, being found on sandy or hard clay 
bottom, and taken in fyke nets set in water from 6 to 14 feet deep. As 
many as 60 to 70 fish are sometimes taken at one lift of a fyke net, but 
as a rule not more than two or three of this number are gravid fish. 
These nets are usually some clistauce from the station, and the fish are 
carried to the hatchery in transportation cans, six or eight being put 
in one can. In some cases this trip is made by water in a sail or row 
boat, while at other times it is made overland by team. The fish arc 
often carried 10 or 12 miles without change of water and without 
apparent injury. A few are caught while the water temperature is 
as low as 33° F., but they are more numerous after the temperature 
reaches 34° or 35° F. On arriving at the station the fish are put into 
wooden tanks supplied with constantly changing water, and here they 
are held until ripe. It is customary to put both males and females in 
the same box or tank. The fish are examined daily and the eggs are 
taken from all which are found to have ripened, the stripped or spent 
fish being released. 

The eggs of the flatfish are quite small, there being 30 in a linear 
inch. Unlike the eggs of the cod, haddock, mackerel, and other marine 
fishes, they do not float, but sink to the bottom of the vessel in which 
they are held. They are not so heavy as those of the lobster, and a 
slight current causes them to rise and carries them to a point where there 
is still water, when they again go to the bottom. When first deposited, 
the eggs are very adhesive and stick together- in one mass or in clusters 
of different sizes. This adhesiveness is overcome, in a measure, by 
thoroughly washing them, and, as this force gradually weakens as the 
eggs become older, usually nearly all the eggs are separate when they 
begin to hatch. The use of dry powdered starch is very effective for this 
purpose; this mixes readily with the saltwater and admirably over- 
comes the glutinosity of the eggs. Its action is purely mechanical. 

In stripping, it is customary to fill a Chester jar with water and place 
inside the jar a bag made of cheese-cloth, into which the eggs are 
allowed to fall. The fish is grasped by the head with the left hand, the 
mouth being in the palm of the hand, and the edge on which the vent 
is located turned from the spawn-taker. The right grasps the fish near 
the tail, and as it is moved with gentle pressure toward the vent, at the 
same time that the left thumb is moving crosswise and exerting similar 
pressure, the eggs are extruded. The milt is then expressed in the 
same way; the eggs are stirred slightly with the hand to thoroughly 
mix them with the milt, and after allowing a short time for the action 



MANUAL OF FISH-CULTURE. 217 

of the milt they are cleaned and the superfluous milt washed off by 
introducing a gentle stream of water into the bag and rolling the eggs 
from side to side. 

It frequently happens that fish held in tanks to mature deposit their 
eggs during the night. In such cases the eggs are found on the bottom 
of the tank the next morning. They are usually in clusters and when 
examined with the microscope it will be found that practically every 
egg is fertilized. 

After the eggs have been taken and fertilized the number is calcu- 
lated by measuring in a glass graduate and computing 47,826 eggs 
to the liquid ounce. The average number of eggs is about 500,000 to 
a fish. On March 6, 1897,30 ounces, or ], 462,000 eggs, were taken 
from a fish 20 inches long and 11 inches wide, its weight being 3£ 
pounds after the eggs were taken. 

Flatfish eggs may be hatched in several kinds of apparatus, but the 
Chester jar is most used, in combination with the McDonald tidal box 
employed in incubating cod eggs. From 400,000 to 500,000 eggs are 
usually placed in each jar. The top of the jar is covered with cheese- 
cloth held in place by rubber bands. The jar is then inverted and 
placed in a tidal box. The usual complement of each box is 2 jars. A 
wooden frame of 1-inch strips is placed lengthwise on the bottom of 
the box for the jars to rest on, so as to raise them and allow the free 
circulation of the water. A hole in the bottom of the jar allows the 
air to pass in and out as the water inside rises and falls. The inner 
compartment, with a bottom of cheese-cloth, used in cod-hatching is 
omitted. 

As in using the jars the eggs are generally on the bottom all the 
time, the experiment has been tried of employing the McDonald box 
with the automatic current in order to keep the eggs in circulation. It 
having been found that the current commonly used for cod eggs caused 
the eggs to pile up in the end nearest the outlet, a stream was intro- 
duced into each end of the box and the water was allowed to escape in 
all directions through a perforated nozzle; the water was kept about 3 
inches deep in the bottom of the box by using a quantity sufficient to 
prevent the breaking of the siphon. By this means a constant current 
is formed, the eggs develop nicely, and the fry hatch, but the current 
necessary to keep the eggs in circulation is strong enough to kill the 
fry by forcing them against the sides of the box. This experiment is 
therefore not considered a success. 

The period of incubation when the mean water temperature is 37° or 
38° F. is 17 or 18 days. 

The fry of the flatfish, although much smaller than those of the cod, 
are much more lively, and are straightened out when first hatched. 
Unlike the young cod, they do not float on the surface, but are scat- 
tered through the water from top to bottom, many being seen among 
the eggs on the bottom of the jars. Unlike the adults, the flatfish fry 



218 REPORT OF COMMISSIONER OP FISH AND FISHERIES. 

swim with the body upright, as young fish of other families do, and 
when first hatched the eyes are on opposite sides of the head. At the 
age of about three months, however, one of the eyes will have moved 
to the other side of the head, to conform with the change of the 
body in swimming from an upright to a fiat position. The position 
constantly assumed by the very young fry is peculiar, the long axis of 
the body being vertical, with the head upward. This is owing to a 
large oil-globule in the anterior part of the yolk-sac. 

The fry are quite hardy and stand transportation very well. They 
have been kept three weeks without change of water in a bottle hang- 
ing in a box of running water to maintain an even temperature in the 
bottle. In planting the fry, which is done in one or two days after 
hatching, they are put into the transportation cans commonly used for 
such purposes and taken in a boat to localities in which the brood fish 
are found. The cans are put overboard and sunk until the mouth is 
submerged, when the contents are gently turned out. For a trip of not 
more than two or three hours' duration, with water temperature about 
38° F., from 400,000 to 500,000 fry may be safely carried in a 10-gallon 
can. 



Report U. S F C. 1897. (To face page 219.) 



Plate 60. 




MISCELLANEOUS MARINE FISHES. 



In addition to the salt-water fishes previously considered, a number of 
others have been artificially propagated by the IT. S. Fish Commission. 
With some of these the fish-cultural work has been rather extensive; 
with others 7 hardly more than experimental. Among those to which 
most attention has been given are tautog, Spanish mackerel, pollock, 
and haddock. Others that have come in for a share of either practical 
or experimental work are sea herring, scup, sea bass, squeteague, 
cunner, sheepshead, and several flounders. 

The same methods of culture mentioned hereafter in connection with 
tautog are applicable in general to scup, sea bass, squeteague, and other 
species having floating eggs. 

THE TAUTOG. 

The tautog ( Tautoga onitis) is a strongly marked species. It belongs 
to a family (Labridce, or the wrasses) characterized in part by one 
dorsal fin, thoracic ventral fins, double nostrils, thick lips, and strong 
teeth in the jaws. The tautog has an elongated body and a large head 
with a convex profile. The rather small mouth is armed with strong 
conical teeth in two series. The eye is small and placed high on the 
side of the head. The body is covered with small scales, in about GO 
transverse rows and 40 longitudinal series. The head is destitute of 
scales, with the exception of a small patch behind the eye. The dorsal 
fin is long and low, with 16 strong spines and 10 soft rays. The anal fin 
contains 3 spines and 8 rays. The body length is 3^ or 3J times that of 
head and 2§ or 3 times the depth. The gillrakers are short, feeble, and 
number only 9. The color of adults is almost uniformly blackish or 
greenish; the young are marked by dark irregular crossbars on a pale 
brownish background; chin, white; iris, bright green. 

The tautog is of considerable importance in certain parts of its range. 
It is found from Maine to South Carolina, but is most abundant in 
Massachusetts, Rhode Islaud, and New York. It is one of the best- 
known shore fishes of the east coast, and goes by a variety of names, 
among which are blackfisb, cbub, oyster-fish, and moll, besides the 
most generally used name of tautog. 

The tautog inhabits principally rocky bottom, where it hides in crev- 
ices, often with its body in an apparently very unnatural position. It 
is quite susceptible to changes in temperature, and during winter enters 
into a state of hibernation in the more northern parts of its range. 
Its coastwise movements are very limited. Its sharp strong teeth 
enable it to consume mollusks and crustaceans, which are its chief 
food; it also eats sand-dollars, worms, and other animals. 

219 



220 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 

The tautog is taken for market in considerable numbers by means of 
lines and traps. It bites quite readily and is a favorite with anglers. 
Its average weight as caught for sale is not more than 2 or 3 pounds, 
but tautog weighing from 6 to 15 pounds are not rare. The maximum 
weight is abont 22£ pounds ; such a specimen from New York, 36£ inches 
long, is preserved in the U. S. National Museum. The annual commer- 
cial catch of tautog is about 1,500,000 pounds, valued at $60,000 ; nearly 
half the yield is from Massachusetts. 

The spawning season on the southern New England coast extends 
from April to August, although June appears to be the principal month. 
The young are very abundant along the shores in the fall. 

The artificial propagation of tautog was experimentally undertaken 
at Woods Hole in 1886. In 1896, 31,431 ,000 eggs were taken in June; 
from these 17,575,000 fry were hatched and planted in neighboring 
waters. 

Tautog from which eggs for hatching are taken are obtained from 
nets or from line fishermen near the station and transferred to live-cars. 
When first brought in they seldom yield any eggs, but in 2 to 6 hours 
they may be stripped of a part of their eggs. The eggs taken after fish 
are held more than 6 hours are usually of no value, and those obtained 
from fish retained one night are invariably worthless. 

The tautog is very prolific. In 1896 a 9|-pound fish yielded 1,142,600 
eggs, and it was estimated that the ovaries contained fully as many 
more eggs that were not yet mature. The average number of eggs per 
fish is from 150,000 to 200,000. 

The eggs of the tautog are about ■£$ inch in diameter. They are 
buoyant, like those of tbe mackerel, and are susceptible of the same 
method of hatching. When placed in the automatic tidal box, they 
hatch in about 5 days, with the water temperature at 69° F., and in 2 
or 3 days with the temperature at 71°. 

The newly hatched fry are transparent and exceedingly small, the 
length being only -^ inch. They are quite hardy and stand transpor- 
tation well. They are planted shortly after hatching. 

THE SPANISH MACKEREL. 

The Spanish mackerel (Scomberomorus maculatus) is the best-known 
fish of the genus and the only one that has received the attention of 
fish-culturists. From the other species of Scomberomorus found on the 
eastern United States coast (S. regalis, the kiugfish, and S. cavalla, 
the cero) this fish is, in part, distinguished by its smaller size and by 
the insertion of the soft dorsal fin in advance of the anal. The body 
is long, the head small and pointed, the mouth large and armed with 
prominent teeth. The anterior dorsal fin has 17 spines, the soft dorsal 
has 18 rays. The anal fin has 2 spines and 17 rays. Behind both the 
dorsal and anal fins are 9 small finlets. The lateral line is wavy and 
has about 175 pores. The general color is silvery, dark-bluish above 
and whitish below. The sides have numerous rounded yellowish spots. 



MANUAL OF FISH-CULTUKE. 221 

This fish is widely distributed, being found on both coasts of North 
America. On the west coast it does not enter United States waters, 
but on the Atlantic seaboard it ranges from Texas to Massachusetts. 
It is especially abundant in the Gulf of Mexico, among the Florida keys, 
in Chesapeake Bay, and on the coast of the Middle Altantic States. 

Its maximum weight is about S3 pounds. Many weighing only 1 or 
1£ pounds are caught for market, and the average is less than 3 pounds. 

The Spanish mackerel is one of the choicest food-fishes of American 
waters; in popular estimation it is scarcely surpassed by any marine 
species except the pompano. It is caught throughout its range on the 
east coast with gill nets, seines, pound nets, and lines. The principal 
Ashing is on the west coast of Florida, on the Louisiana coast, in the 
lower part of Chesapeake Bay, and on the coasts of New Jersey and New 
York. The approximate annual value of the catch at present is $130,000, 
which represents 1,700,000 pounds. In 1880 the output was 1,887,000 
pounds, having a value of $132,000. The yield in the Middle States is 
much less than formerly, while in the Gulf States it has increased. 

The fish spawns throughout its entire range on the United States 
coast. The spawning season is quite prolonged, extending from April 
in the Carolinas to September in New York, and in a given locality 
continues from six to ten weeks. All of the eggs in the ovaries of a 
given fish do not mature at one time; eggs in all stages of development 
may be found, suggesting a comparatively long spawning season for 
individual fish as well as for the species as a whole. The eggs, when 
laid, float at the surface, where they are driven about by wind and tide. 
Doubtless a large percentage of the eggs do not hatch, through failure 
of fertilization and by being stranded. The eggs are very small, their 
diameter being only -^ to - 2 - 2 - of an inch. 

The artificial impregnation and hatching of Spanish mackerel eggs 
were first accomplished in 1880, since which time the propagation of 
the fish has been taken up on a number of occasions, although the 
work in any one season has been comparatively limited. 

The serious diminution in the supply of this species in certain sec- 
tions seems to call for its artificial cultivation whenever it can be taken 
up without detriment to the propagation of other more or equally 
important fish. 

In the work of artificially propagating this fish recourse has been 
had to the nets of commercial fishermen for the supply of spawn and 
milt. Chesapeake Bay has been the seat of the principal operations, 
which have been conducted by the steamer Fish Hawk. The catch of 
Spanish mackerel in this bay in pound nets and other appliances is 
very large, and the facilities for fish-cultural work of this character 
are doubtless superior to those of any other section, with the possible 
exception of the west coast of Florida. 

The necessity for depending on the fishermen for the supply of eggs 
is somewhat detrimental to the best results and prevents extensive 
work, although the owners of fishing apparatus heartily cooperate. 



222 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 

Owing to tbe fact that the fish appear to spawn mostly at night, 
when the pound nets are lifted in the morning the ripe eggs have in 
many cases been extruded before the spawn-taker could secure tbem. 
The injuries which the fish sustain while in the pound nets and during 
the hauling of the nets appear to seriously affect the eggs and cause 
the non-hatching of a comparatively large percentage. Undoubtedly 
better results may be obtained if a number of nets are fished exclu- 
sively for this purpose, insuring the careful removal of fish at the best 
times for taking and fertilizing the eggs. 

The eggs are very delicate and susceptible to meteorological influ- 
ences. Their development is markedly affected by water temperature 
and atmospheric conditions; electrical disturbances, as with other fish 
eggs, are injurious, but to what extent and in what way are not known. 
The largest number of ripe eggs thus far taken from a single specimen 
is 60,000, but the average is only 20,000. 

The Chester jar, such as is used in hatching flatfish eggs, has been 
found the best apparatus for Spanish mackerel eggs. If the jars are 
kept clean and not overcrowded, a constant current of water does not 
seem to be essential; of a lot of 60,000 eggs in a jar of quiet water, 90 
per cent hatched. The cod tidal-box is also adapted to this work. 

In ordinary bay water having a density of 1.014 to 1.019, the eggs 
are buoyant and remain at the surface until hatching ensues; but in 
water of low specific gravity they sink and give unsatisfactory results. 
The period of incubation is very short. Under normal conditions eggs 
hatch in 20 to 30 hours, averaging 25 hours, at a temperature of 77° 
or 78°. The fry are planted soon after hatching. 

HADDOCK, POLLOCK, AND OTHER GADID^. 

The methods of culture employed with the cod are applicable to other 
members of the cod family having buoyant eggs. The United States 
Fish Commission have frequently taken and hatched eggs of the pollock 
(Pollachius virens) and the haddock (Melanogr animus cegliftnus). Both 
are important food-fishes, but much less valuable than the cod, and the 
collection of eggs has generally been only supplemental to cod work. 

The pollock is found from New Jersey northward. It goes in large 
schools, which are often found at the surface, thus differing from the 
cod and haddock. The average weight is 9 or 10 pounds, and the 
maximum about 30 pounds. Fishing is chiefly done from small vessels 
and boats, and is most important in Massachusetts. The value of the 
annual catch is about $100,000. The pollock is an excellent food-fish 
in both a fresh and a salted condition. ' - 

The eggs of the pollock have at times been gathered in large num- 
bers in the vicinity of Gloucester; during some seasons about 40,000,000 
eggs have been taken. The eggs measure about ^V inch in diameter. 
The pollock spawning season includes the months of October, Novem- 
ber, and December. The fish from which eggs are obtained are taken 



MANUAL OF FISH-CULTUEE. 223 

with nets and lines by commercial fishermen; the average number of 
eggs to a fish is from 200,000 to 250,000. The period of incubation is 
somewhat shorter than that of the' cod, being 9 days at 43° and 6 days 
at 49°. About 5 days are required for the absorption of the yolk-sac. 

The haddock ranges from Delaware northward, and is, as a rule, very 
abundant on the "banks" lying off the New England shore. In its 
habits it is similar to the cod, frequenting the same grounds and being 
caught at the same time. Its average weight is about 4 pounds and 
the maximum under 20 pounds. The fishery is very extensive in Mas- 
sachusetts, most of the catch being landed fresh in Boston. The 
annual yield is about 50,000,000 pounds, worth $1,115,000. 

The artificial propagation of haddock has been conducted chiefly at 
Gloucester, where as many as 30,000,000 eggs have been collected in a 
single season. The eggs are about --fa- inch in diameter, and are quite 
delicate and tender. The spawning time extends from January to 
June. The average production of eggs per fish is about 100,000. 

The eggs are slightly glutinous and have a tendency to form into 
small lumps during hatching. At a mean temperature of 37° they 
hatch in 15 days, and at 41° in 13 days. The yolk-sac is absorbed in 
10 days at a temperature of 41°. 

The tomcod or frostfish (Microgadus tomcod) has been extensively 
propagated by the New York Fish Commission. It is a small but 
excellent food-fish, found along the Atlantic coast from New York to 
the Bay of Fundy. It is most abundant in early winter, when it 
approaches the shores and ascends streams for the purpose of spawn- 
ing. It rarely exceeds 10 or 12 inches in length. 

THE GUNNER. 

The eggs of the cunner or chogset ( Ctenolabrus adspersus) are of the 
same size and character as those of its near relation, the tautog, and 
are deposited during the same season. Iu water having a mean tem- 
perature of 56° F. they have been hatched in 5 days, in the tidal cod-jar. 
On account of the small size, great abundance, and comparatively 
little commercial value, the propagation of the cunner has not been 
regularly undertaken. 

THE SCUP. 

The scup (Stenotomus chrysops) is a rather important small food-fish 
found along the Atlantic coast from Cape Ann to South Carolina; it is 
most abundant in southern New England. It spawns in June. The 
eggs are -^ inch in diameter and hatch in 4 days at a mean tem- 
perature of 62° F. 

THE SEA BASS. 

The eggs of the sea bass (Gentropristes striatus) are of the same size 
as scup eggs, are deposited in June, and hatch in 5 days with the 
water temperature 59° or 60°. The sea bass is an important food-fish, 



224 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 

found from Massachusetts to Florida ; it is taken in large quantities 
from New Jersey northward with lines and traps. It attains a weight 
of 5 pounds, but the average weight- is only L or 1£ pounds. 

THE SQUETEAGUES. 

The squeteague or weakfish (Cynoscion regalis) is a prominent food- 
fish of the Atlantic and Gulf coasts, the northern limit of its range 
being in the vicinity of Cape Cod. It goes in immense schools and is 
taken in large quantities for market, in North Carolina, Chesapeake 
Bay, Delaware Bay, on the New Jersey and New York coasts, and in 
southern New England. It varies greatly in size; the average weight 
is under 5 pounds, but it has been known to attain a weight of 30 
pounds. In the vicinity of Woods Hole this fish spawns in June. Its 
eggs are -£% inch in diameter, and at an average temperature of 60° F. 
hatch in 2 days. 

The spotted squeteague or "sea trout" (Cynoscion nebulosum) has 
also been propagated on a small scale. It is a valuable food- fish from 
Chesapeake Bay southward, being taken in largest quantities in Vir- 
ginia, North Carolina, Florida, and the Gulf States. Its average weight 
is 2 pounds and its maximum 10 pounds. It spawns in bays and sounds 
in spring and summer, the time varying with the latitude. The eggs 
are buoyant, 3V inch in diameter, and hatch in about 40 hours at a 
temperature of 77° F. This species has been artificially hatched on 
the southwest coast of Florida by the steamer Fish Rawh. 

THE SHEEPSHEAD. 

The sheepshead (Archosargus probatocephalus) is generally regarded 
as one of the best food fishes of American waters. Its deep body, of a 
grayish color, marked by 8 transverse black bauds, and its peculiarly 
shaped head, with mouth armed with prominent incisor teeth, make it 
readily recognized. It ranges from Cape Cod to Texas, but is most 
abundant from Chesapeake Bay southward. It attains a weight of 
over 20 pounds, but the average weight on the Atlantic coast is not 
over 7 or 8 pounds, and in the Gulf of Mexico scarcely exceeds 3 pounds. 
In southern waters the fish is a permanent resident, but in the northern 
part of its range it is found only during spring, summer, and autnmn. 
The spawning season is from March to June, according to the locality. 

The artificial hatching of the sheepshead has been undertaken on 
several occasions, but is not regularly prosecuted. The inost extensive 
work was conducted by the Fish SawTc in March and April, 1889, when 
23,400,000 eggs were taken in the vicinity of San Carlos Bay, on the 
southwest coast of Florida. These yielded 16,500,000 healthy fry, most 
of which were planted in local waters. 

In capturing spawning fish on the Florida coast it was found that 
the best time to use the seine was just before sundown, as the flood tide 
was about to "make." The fish were then easily taken in large numbers. 
Seine hauls in the morning consisted only of male fish. Spawning 



MANUAL OP FISH-CULTURE. 225 

sheepshead swim in schools, and seem to prefer sandy beaches, along 
which they resort at a depth of 6 or 8 feet. 

The sheepshead egg is very small, transparent, and of less specific 
gravity than sea water. The diameter is ■£%. of an inch, and the number 
in a fluid ounce is about 50,000, or 1,600,000 in a quart. 

The eggs are satisfactorily incubated in the tidal cod-jar, about 
300,000 eggs being placed in each jar. The development is very rapid, 
and in the warm water of the Gulf (76° or 77° P.) the eggs hatch in 40 
hours. The newly hatched fry are very small, but active and strong, 
aud withstand considerable rough handling. They are planted when 
72 to 80 hours old. 

It is probably not practicable to carry on extensive sheepshead 
hatching north of Florida, although small quantities of eggs could 
doubtless be taken in North Carolina and Virginia. 

THE SEA HERRING. 

The sea herring (Clupea liarengus) may be distinguished from other 
clupeoid fishes found in United States waters by the following char- 
acters : Body elongate and laterally compressed, the- depth contained 
4£ times in length; mouth at end of snout; lower jaw projecting, 
extending to beneath the middle of eye; roof of mouth with an ovate 
patch of small teeth; gillrakers long and slender, about 40 below 
the angle in adults, fewer in young; dorsal fin with 18 rays, inserted 
slightly behind middle of body; ventral fins beginning beneath middle 
of dorsal; anal fin with 17 rays; median line of belly with 28 weak 
spines or scutes in front of ventral fins and 13 behind fins; scales thin, 
easily detached, posterior edges rounded, 57 in lateral series; color 
bluish or bluish-green above, light-silvery below. 

The sea herring exists in great abundance on both shores of the 
Atlantic Ocean north of the latitude of about 37° north. On the coast 
of North America it is not regularly abundant south of Cape Cod, but 
it is occasionally found as far south as Chesapeake Bay. In number of 
individuals this species is probably exceeded by no other fish. On the 
Pacific Coast a similar and almost equally abundant species (Clupea 
pallasii) is found from Alaska to Mexico. 

There are no well-defined movements of the herring on the west 
shore of the Atlantic, if those induced by the spawning instinct are 
excepted. There was formerly a distinct shoreward migration, during 
the winter months, in the Bay of Fundy, but this run has not occurred 
for a number of years. In many places the herring, especially the 
smaller individuals, appear to be resident in the shore waters. The 
maximum length of this fish is about 17 inches, and the usual length of 
spawning fish on the United States coast is from 11 to 14 inches. 

The herring subsists on minute invertebrates, chief among which are 
copepods, larval worms, and larval mollusks. In turn it is consumed 
in enormous quantities by cod, haddock, sharks, and many other fishes. 

F. C.E. 1897 15 



226 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 

With respect to the time of spawning, the herring may be divided 
into two groups, one spawning in the spring, in April, May, and June, 
and the other between July and December. The spring spawning 
occurs entirely east of Eastport, Maine, and the fall spawning princi- 
pally, but not altogether, west of that place. Probably the greatest 
spawning grounds south of the Gulf of St. Lawrence are at Grand 
Manan, where the eggs are deposited principally in July, August, and 
September. Thence the season becomes progressively later westward, 
on the coast of Maine occurring between September 1 and October 15; 
on the eastern coast of Massachusetts, between October 1 and Novem- 
ber 1, and south of Cape Cod from October 15 to December 1. 

The female herring of average size deposits between 20,000 and 47,000 
eggs at a spawning, the usual number being not far from 30,000. The 
eggs are deposited upon the bottom, and, being covered with a glutinous 
material which soon hardens in contact with the water, they become 
firmly attached to extraneous materials, to which they often adhere in 
masses as large as a walnut. The egg measures about -<fa inch in 
diameter, and is usually polyhedral from mutual pressure exerted by the 
eggs in masses. 

The commercial value of the sea herring is almost incalculable. It is 
undoubtedly the most important of food-fishes, although in the United 
States it is exceeded in economic value by many marine and fresh-water 
species. Some time ago the annual yield of the world was estimated 
at 3,000,000,000 herring, weighing 1,500,000,000 pounds, the principal 
part of which was taken in Norway. In the JSTew England States the 
annual catch is about 55,000,000 pounds, with a first value of $350,000. 
The fish is taken chiefly with seines and weirs, and about five-sevenths 
of the yield is obtained on the coast of Maine. The market value of 
the output is greatly enhanced by the salting, smoking, and canning 
processes to which a large part of the catch is subjected. In Maine the 
canning of young herring as sardines is a very important industry. 
Fresh herring are used chiefly for bait in the line fisheries for cod and 
other "ground fish." 

Experiments in the artificial propagation of the herring have been 
conducted both in this country and in Europe, but owing to the great 
abundance of the species the work has not been carried beyond this 
experimental stage. In the United States there has as yet been no 
permanent diminution of the supply that renders the cultivation of the 
species necessary, notwithstanding an extremely large fishery and the 
sacrifice of enormous quantities of very small fish. 

The first successful attempt to propagate this fish was in 1878, in 
Germany, when elaborate experiments were made. In the same year 
the artificial hatching of the species was accomplished by the United 
States Fish Commission. The eggs, owing to their cohesion into masses, 
showed a tendency to molding, but this difficulty could doubtless be 
obviated by the use of starch, as with other cohesive eggs. 



MANUAL OF FISH-CULTURE. 227 

Development takes place in water ranging in temperature between 
33° and 55° ¥., the time of incubation varying from about 40 days at the 
former temperature to 11 or 12 days at the latter. Sudden and extreme 
variation between the temperature limits mentioned had little or no 
effect except to retard or accelerate the hatching in accordance with 
the rule just mentioned. When water of a temperature lower than 
33° F. was used many of the embryos were deformed. The degree of 
salinity of the water does not appear to exert much influence upon the 
hatching of the eggs. . 

THE SAND-DAB AND FOUR-SPOTTED FLOUNDER. 

Besides the flatfish or winter flounder, two other flounders have been 
artificially hatched, on a small scale, at Woods Hole; these are the 
sand-dab (Bothus maculatus) and the four-spotted flounder {Paralichthys 
oblongus). The eggs of both fish are buoyant, and deposited in May. 
Those of the former are -$% inch in diameter, and of the latter ■£$ inch. 
The period of incubation at a temperature varying from 51° to 54° F. 
is about 8 days. 



■Report U. S. F. C. 1897. (To face page 229.) 



Plate 61, 




HOMARUS AMERICANUS. American Lobster. 



THE AMERICAN LOBSTER. 



DESCRIPTION. 



The lobster (Homarus americanus) belongs to that group of the Crus- 
tacea called the Decapoda, because all of its members are provided with 
ten feet, more or less adapted for walking. To the Decapoda also belong 
the crabs and the shrimps, prawns, and crayfish. The crabs are less 
related to the lobster than the other forms mentioned, and may be 
readily distinguished from them by the relatively great breadth of the 
body and the small size of the abdomen or tail, which is doubled under 
the thorax to form the " apron." The lobsters, crayfish, shrimps, etc., 
are elongate forms with the tail or abdomen very large and extended 
more or less in the same horizontal plane with the anterior part of the 
body. The lobster and the crayfishes are somewhat closely related, but 
differ, among other characters, in the number and structure of the gills 
and in the relative size of the flat plate or scale which is attached at 
the base of the antennae or long feelers. The Pacific Coast crayfishes 
have 18 gills, those east of the Rocky Mountains have 17, while the 
lobster has 20. The appendage of the antenna is large in the cray- 
fishes, but very small in the lobster. Moreover, the crayfishes rarely 
exceed 5 or 6 inches in length, while the adult lobster is much larger, 
as seen in the markets, seldom measuring less than -9 or 10 inches. 
The spiny lobster, the " lobster" of the Pacific Coast, is readily distin- 
guished from the crayfish and the common lobster by the total absence 
of great claws, by the greater length and stoutness of the antennae, and 
by the presence of large, broad-based, spinous processes on the back. 

The body of the lobster is divided into two distinct regions, the 
cephalothorax and abdomen. The former consists of the head and 
thorax fused into one united whole. That portion which would consti- 
tute the head, were it separate, bears the eyes, the two pairs of feelers, 
and the mouth, with the several pairs of modified limbs which surround 
that organ and aid in tearing up the food and passing it between the 
lips. The thoracic portion of the cephalothorax is furnished with five 
pairs of stout limbs, the first pair bearing the great claws, which are 
rarely of the same size on the two sides, and the last four pairs being used 
in walking. From the fact that this portion of the body bears five pairs 
of apxjendages, it is assumed that it represents five fused segments. 

The abdomen is narrower than the cephalothorax and is composed 
of six separate segments movable on one another. In the female the 

229 



230 REPORT OF COMMISSIONER OP PISH AND FISHERIES. 

first five pairs of abdominal appendages, known as swiinmerets, are all 
similar and consist of a short basal piece and two terminal pieces side 
by side. The appendages of the sixth segment consist of the same 
arrangement of parts, but the pieces are broad and paddle-like, and, 
with the terminal plate attached to the last segment, constitute a 
powerful caudal paddle or tail. In the male the abdomen is narrower 
than in the female, and the first two pairs of swimmerets differ much 
from those which follow. 

The color of the lobster is subject to great variation, but most fre- 
quently is dark bluish-green above, mottled with dark-green blotches ; 
there is usually more or less red or vermilion on the appendages, 
especially on the tubercles, tips, and under side of the great claws 
and on the antennae; the walking legs are light blue with reddish tips 
and tufts of hair. Occasionally specimens are found which are almost 
entirely red, and more frequently they are blue or bluish in general tone. 

DISTRIBUTION AND ABUNDANCE. 

The lobster is found from Labrador to Delaware, its range covering 
about 1,300 miles of coast line. Stragglers have been taken on the 
coasts of Virginia and North Carolina. While the bathic range is prac- 
tically limited by the 100-fathom line, it is occasionally found long 
distances from land on the fishing-banks off the New England coast. 

The lobster is most abundant in the northern part of its habitat. 
On the United States coast it is most numerous in Maine. In the 
provinces of Nova Scotia, New Brunswick, and Quebec, and also in 
Newfoundland it is extremely abundant. 

MOVEMENTS. 

The movements of the lobster are chiefly on and off shore. Such 
coastwise movements as characterize the mackerel, bluefish, and men- 
haden are never undertaken by the iobster. This fact makes possible 
the rapid depletion of fishing-grounds, and even the practical exter- 
mination of the lobster in given areas; it also affords basis for the 
belief in the efficacy of artificial means for maintaining and increasing 
the supply. 

There are well-marked movements of the lobster induced by various 
influences, among which are the abundance or scarcity of food, the 
water temperature, and the spawning instinct. On the United States 
coast there is in the spring months a shoreward movement of large 
bodies of lobsters; -on the approach of winter the lobsters move out 
into deep water. 

FOOD. 

The principal food of the lobster is fish, either dead or alive. Such 
bottom species as the sculpin, flounder, and sea-robin can doubtless be 
readily caught by the lobster, and they also consume a large number 
of invertebrates, among them being crabs and other crustaceans, clams, 
conchs, and other mollusks, starfish, sea-urchins, etc. Lobster eggs 



MANUAL OF FISH-CULTURE. 231 

have been found in a lobster's stomach, and algse sometimes serve as 
food. Fish is the bait most extensively employed in the lobster fishery. 

REPRODUCTION. 

The reproductive function of the lobster is not generally understood, 
and until a comparatively receut date a number of important questions 
in relation thereto were undecided. From the standpoints of the com- 
mercial fishermen, fish-culturist, and legislator, it is necessary that the 
principal phases of this subject be clearly appreciated, in order that 
the supply may be maintained. 

The principal spawning season for lobsters on the United States coast 
is summer, especially July and August, when probably three-fourths of 
the lobsters deposit their eggs. The remaining egg-producing lobsters 
lay during the fall and winter. A given lobster does not spawn oftener 
than every second year, as has been shown by recent studies conducted 
by the Commission. 

The eggs are fertilized outside the body of the female. The sper- 
matic fluid is deposited in a receptacle at the base of the third pair of 
walking legs, and retains its vitality for a long time. When the eggs 
are being extruded, the female lobster lies on her back and folds the 
tail so as to form a kind of chamber to retain the eggs. After their 
discharge from the body, the eggs become coated with a cement substance 
secreted by glands in the swimmerets; this substance hardens after 
being in contact with the water and firmly unites the eggs to the hair- 
like filaments on the swimmerets. The exact method by which the 
fertilizing principle is conveyed to the eggs from the pouch in which it 
is contained is not known. 

The incubative period is much prolonged. After the eggs are 
extruded and become attached externally, they are carried 10 or 11 
months before hatching ensues ; during this time they are carefully 
protected, and are perfectly aerated by the active motion of the swim- 
merets. On the United States coast most of the lobsters emerge from 
the egg in June, although some of the hatching is completed in May 
and some in July or even later. A few eggs are now known to hatch 
in winter. All of the embryos do not come from the eggs at the same 
time, the hatching occupying a week or more. The young receive no 
attention from the adults, but lead an independent existence immedi- 
ately after escaping from the egg. 

The lobster egg is about -^ inch in diameter. When newly laid it is 
usually of a dark-green color, but is sometimes ligh^-grayish or yellow- 
ish-green. 

The known maximum number of eggs produced at one time by a 
lobster is 97,440; the average from lobsters taken for market is 10,000 
to 12,000. The number depends largely on the size of the lobster, 
apparently in conformity to the following rule: The numbers of eggs 
laid by given lobsters vary in a geometric scale, while the lengths of 
the lobsters vary in an arithmetic scale. 



232 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 

The following table illustrates, with approximate accuracy, the egg- 
producing capacities of lobsters of the lengths indicated under normal 
conditions : 



Length of lobster. 


Number of 
eggs laid. 




5,000 
10, 000 
20, 000 
40, 000 
80, 000 













MOLTING AND GROWTH. 

The act of shedding the shell, or molting, is important and critical. 
It is only after shedding that growth takes place; during the early 
stages of the lobster's existence this function is often exercised in a 
comparatively short time, while later it occurs only at long intervals. 
Molting in the lobster consists in throwing off the entire external skele- 
ton, together with the lining of the digestive tract. 

The first molt takes place about the time the young emerges from 
the egg, when it is about a third of an inch long, and many lobsters 
do not survive this. During this first stage the larval lobster swims 
at or near the surface. A second molt ensues in from 1 to 5 days, and 
the lobster enters on its second stage, its average length being about 
two-fifths of an inch and its habits similar to the first stage. In 2 to 
5 days another molt takes place, and the length of the larva increases 
to about half an inch. This is followed in 2 to 8 days by another molt, 
and the lobster enters on the fourth stage, when its length becomes 
slightly greater. From 10 to 20 days later the fifth molt ushers in the 
fifth stage, after which the surface- swimming habit is discarded and the 
larva goes to the bottom and begins to assume the characteristics of the 
adult. This stage lasts 11 to 18 days, and in it the young lobster has 
attained a length of about three-fifths of an inch. From this time on the 
molts are at longer and longer intervals until the fully mature condition 
is reached, when shedding takes place only once in one or two years. 

The food of lobsters during the larval stages consists chiefly of small 
crustaceans. A, very pugnacious instinct then characterizes them, and 
active cannibalism prevents their artificial rearing for lack of abundant 
natural food. 

Larval lobsters are very susceptible to the influence of the sun (helio- 
tropic) while in the first three stages, being attracted by bright rays 
to the surface of the ocean or to the side of a vessel. This peculiarity 
is lost during the fourth stage. 

During the first year the young lobster, which since the fourth stage 
has become more and more like the adult in form and habits with each 
molt, attains a length of about 2 or 3 inches. At the end of the second 



MANUAL OF FISH-CULTURE. 233 

year the length is 5 to 7 inches. By the end of 4£ or 5 years a length 
of about 10 inches is reached. The rate of growth, however, depends 
greatly on the environment, the abundance of food being a very impor- 
tant factor. 

The adult lobster usually molts in summer, and in the case of the 
female, shortly after the hatching of the eggs, As several months are 
required for the new shell to acquire the hardness of the old ; as newly- 
laid eggs are rarely found on a soft-shell lobster; as molting does not 
ensue while the eggs are on the swiminerets; and, furthermore, as 
dissection has shown that the ovaries of a lobster whose eggs have 
recently hatched are in an immature condition and will not yield eggs 
until the succeeding year, it follows that the mature lobster deposits 
eggs not oftener than once in two years, with an alternating molt. 

SIZE AND WEIGHT. 

The average size of lobsters caught for market is now much less than 
it was in the earlier days of the fishery, and their average weight is 
probably not over 2 pounds. A lobster 9 inches long weighs, on an 
average, 1% pounds; a 10^-inch lobster, If pounds; a 12-inch lobster, 3 
pounds; and a 15-inch lobster, 4 to 5 pounds; while a lobster 20 inches 
long weighs 20 pounds or more. Lobsters weighing as much as 15 or 
20 pounds are uncommon, and those weighing over 20 pounds are very 
rare. Up to a recent date, the largest lobster of authenticated weight 
wat about 25 pounds. In 1897, however, 3 lobsters, each weighing over 
30 pounds, were taken off Sandy Hook, N". J., the weight of the largest 
being 33 pounds. 

The male lobster weighs more than the female of the same length, 
the difference in 11 -inch lobsters, for instance, being about a quarter 
of a pound. 

The size at which the lobster attains sexual maturity is a very 
important question. In the New England and Middle States and the 
Canadian Provinces the laws relating to the minimum size of market- 
able lobsters are quite various and illustrate the absence of definite 
information on this subject. In Maine, Massachusetts, New Hamp- 
shire, and New York the minimum limit of size of lobsters that maybe 
sold is now 10 J inches; in Ehode Island it is 10 inches, and in Con- 
necticut it is 9 inches. In the British Provinces the limit is much 
lower than in Maine. 

Investigations conducted by the Fish Commission on the NewEngland 
coast show that the female lobster attains maturity when from 8 to 12 
inches long. Comparatively few lobsters under 9 inches in length 
lay eggs. Of over 1,000 egg-bearing lobsters collected at Woods Hole 
during a period of years, less than 2 per cent were under 9 inches long. 
On the other hand, by the time they have reached the length of 10£ 
inches most lobsters will have produced eggs, and this should be the 
minimum size permitted in the markets. 



234 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 

COMMERCIAL VALUE. 

The lobster is the most important crustacean of the United States. 
It is the object of a special fishery, carried on with pots or traps, in all 
the coastal States from Delaware northward, and also in Nova Scotia, 
New Brunswick, Prince Edward Island, Quebec, and Newfoundland. 
In Maine, where the fishery is more important than in any other State, 
the lobster is the principal fishery product. In 1892 over 3,500 persons 
were engaged in this fishery in the United States: the capital invested 
was about $650,000, and the catch amounted to 23,725,000 pounds, 
valued at $1,062,000. In 1880 the yield was but little smaller (20,240,000 
pounds), but the market value was much less, being only $488,000. 

Between 1889 and 1892 the New England lobster catch decreased 
over 7,000,000 pounds, or 23 per cent, while the value increased over 
$200,000, or 25 per cent. For a number of years this fishery presented 
the anomaly of a diminishing supply and an augmented catch, owing 
to the more active prosecution of the business; but the decline in the 
yield has for some time been unchecked, notwithstanding the employ- 
ment of more apparatus and the prolongation of the fishing season. 
With a singular disregard for their own welfare, many fishermen have 
continually violated the State laws for the protection of small, imma- 
ture lobsters and females bearing eggs. Only the rigid enforcement of 
restrictive measures by the States and the extensive artificial propaga- 
tion of the lobster can ward off the destruction which threatens this 
valuable fishery. 

INCEPTION AND PROGRESS OF LOBSTER-CULTURE. 

If egg-bearing lobsters were not liable to destruction by man, arti- 
ficial propagation would hardly be necessary. Notwithstanding the 
enactment of stringent laws prohibiting the sale of " berried "lobsters, 
the frequent sacrifice of such lobsters, with their eggs, and of many 
immature lobsters, has seriously reduced the lobster output and rendered 
active and stringent measures imperative. By the present methods 
millions of lobster eggs are annually taken and hatched that would be 
lost, and the females producing them, amounting to several thousands, 
are liberated. 

Prior to 1885 experiments had been conducted at various points look- 
ing to the artificial propagation of the lobster. The only practical 
attempts of this nature previous to those made by the Fish Commission 
were by means of " parking," that is, holding in large naturally inclosed 
basins lobsters that had been injured, soft-shelled ones, and those below 
marketable size. Occasionally female lobsters with spawn were placed 
in the same inclosures. One of these parks was established in Massa- 
chusetts in 1872, but was afterward abandoned ; another was established 
on the coast of Maine about 1880. It was soon demonstrated, however, 
that the results from inclosures of this character, so far as the rearing 
of the lobsters from the young were concerned, would not be sufficient 
to materially affect the general supply. 



MANUAL OF FISH-CULTURE. 235 

The completion of the new marine laboratory and hatchery at Woods 
Hole in 1885, with its complete system of salt-water circulation, per- 
mitted the commencement of experiments in artificial hatching on a 
large scale, which had not been practicable theretofore, although small 
quantities of lobster eggs, as well as those of other crustaceans, bad 
been successfully hatched. In 1886 the experiments had progressed so 
successfully that several million eggs were collected and hatched at 
Woods Hole, the fry being deposited in Vineyard Sound and adjacent 
waters. From 1887 to 1890, inclusive, the number of eggs collected 
was 17,821,000. 

From the eggs collected up to 1889 the average production of fry was 
about 54 per cent. During these years experiments were conducted as 
to the best method of hatching the eggs. The various forms of appa- 
ratus used were the Chester jar, the McDonald tidal box, and the 
McDonald automatic hatching-jar. In 1889 the results secured in the 
latter form of apparatus were so much better than with the others that 
it was adopted, and in 1890, from the 4,353,000 eggs collected, over 81 
per cent yielded fry. Work was continued at Woods Hole on about 
the same scale until 1894, when the collections aggregated 97,000,000 
eggs. In the same year lobster propagation was undertaken at Glouces- 
ter and a collection of 10,000,000 eggs was made there. 

During the fiscal year 189'> the number of eggs taken by the Fish 
Commission was 105,188,000, the resulting fry liberated numbering 
97,579,000, or about 93 per cent; and in 1897 the collections amounted 
to 150,000,000 eggs, of which 135,000,000, or 90 per cent, were hatched. 

COLLECTION OF EGG-BEARING LOBSTERS. 

Although the new eggs appear on the lobsters during the months of 
July and August, no special effort is made to secure egg-bearing 
lobsters until the following spring. The collections usually commence 
in April and continue until the middle of July. At Woods Hole it 
has been the recent practice to receive at the station and place in the 
hatching-jars during the fall and winter any lobsters having external 
eggs that may be captured by local fisherman. The collecting-grounds 
extend from New London, Connecticut, to Rockland, Maine. For Woods 
Hole station eggs are secured from fishermen operating between New 
London, Connecticut, and Plymouth, Massachusetts. 

The most important grounds in Connecticut are in the vicinity of New 
London and Noank; in Massachusetts, New Bedford, South Dartmouth, 
Plymouth, Woods Hole, and numerous localities in Buzzards Bay and 
Vineyard Sound. Eggs for the Gloucester station are secured from the 
fishermen operating between Boston and Rockland, which territory 
comprises the most important lobster fishery in the United States. The 
schooner Grampus is used in making the collections between Portland 
and Rockland, the lobsters being delivered at Gloucester early in the 
season and later on to the steamer Fish Hawk, which is stationed at a 
suitable point in Casco Bay. 



236 EEPORT OF COMMISSIONER OF FISH AND FISHERIES. 

As the laws of Massachusetts, New Hampshire, and Maine prohibit 
the holding of the "berried" lobsters by the fishermen, arrangements 
are made with the State authorities by which certain officials of the Fish 
Commission are appointed deputy wardens and authorized to hold egg- 
bearing lobsters for fish-cultural purposes in live-boxes. Early in the 
spring all of the lobster fishermen in the territory referred to above are 
visited by agents of the Commission, who arrange with them to hold 
all of their egg lobsters in live-cars until called for, at a price agreed on. 

Collections are made from Woods Hole and Gloucester by steam 
launches and sailing vessels. The steam launches visit the near points 
three to four times a week to obtain egg-bearing lobsters. The vessels 
collect at more distant points in Connecticut and Maine. Local agents 
at Boston and Plymouth, Massachusetts, and Kittery Point, Maine, 
also collect egg-bearing lobsters, which are held in live-boxes until the 
agent has a sufficient number to make a trip. On the arrival of the 
vessel or launch at the station the lobsters are transferred to tanks 
supplied with running water and held until the spawn-taker is ready to 
strip the eggs. 

TAKING AND MEASURING THE EGGS. 

The receptacle into which the spawn-taker strips the eggs from a 
lobster is either a glass jar (9 inches in diameter) or a water-bucket, 
Avhich, after thorough cleanings is partly filled with water. 

The operator, with his left hand, grasps the lobster from above and 
turns it on its back, lowering it into the spawning-vessel head down- 
ward. By pressing it firmly against the sides of the jar it is prevented 
from using the anterior part of its body or its mandibles. The hand is 
then slipped farther back toward the tail and the segmented portion of 
the body is held firmly to prevent its closing. The lobster is then ready 
for stripping. A rather dull, short-bladed knife is used to separate 
the eggs from the swimmerets, to which they are attached by hair- like 
fibers; stripping begins at the last pair of swimmerets and gradually 
proceeds toward the body. As the eggs are scraped oft' they fall into 
the water in the jar. Some which adhere to the claws of the lobster 
are washed off' by means of a small stream of water. The lobster is 
then put back into a tank, where it remains until liberated. 

Lobsters received by the local agents at Boston and Kittery Point 
are held until a suitable quantity is on hand and are then stripped, the 
eggs being taken to the station in transportation cans and the adults 
released. Early in the spring the eggs stand transportation well, but 
late in the season, as incubation becomes more advanced, they are very 
delicate and are quickly affected by rough handling or sudden changes 
in temperature. 

Before being transferred to the hatching-vessels the eggs are accu- 
rately measured, generally with a glass graduate, into which they are 
poured, the water being drawn off. The basis of measure is an ounce, 
which contains about 6,090 eggs. 



MANUAL OF FISH-CULTURE. 237 

HATCHING APPARATUS AND OPERATIONS. 

Experiments conducted during a series of years having demonstrated 
that the automatic hatching-jar was the best form of apparatus for 
hatching lobster eggs, it has been adopted at the stations of the Com- 
mission since 1889. A full description of this jar is given in the article 
on shad-culture, pp. 150-152. The manipulation and operation of the jar 
is practically the same as with shad eggs, except that frequently, where 
the water supply is inadequate, three jars are connected by means of 
rubber tubing and the water used over and over. This is accomplished 
by connecting the overflow from the first jar with the supply to the 
second and so on, but can only be done during the early stages before 
the fry commence to hatch. When first placed in the jar the eggs are 
matted together by the fine hair-like fibers, but after a few days they 
separate and work very much like shad eggs. 

From 400,000 to 500,000 eggs (equivalent to about 2 to 2£ quarts) are 
usually placed in each jar, although at times when the hatchery is 
crowded a few more may be successfully cared for. 

The fry pass voluntarily from these jars to cylindrical glass jars, 9 
inches in diameter and either 9 or 18 inches high, placed in the center 
of the table and covered with cheese-cloth at the top to prevent their 
escape. 

The period of incubation depends entirely upon the age of the egg 
when collected. For example, eggs taken in October do not hatch until 
the following May, whereas eggs collected in June frequently hatch 
in 24 hours after being placed in the jars. During one season eggs 
collected from December 12 to January 25, numbering 1,717,000, at a 
temperature of 45°, commenced hatching May 25 at a temperature of 
54°. To determine how soon the new-laid eggs can be taken from the 
parent and hatched artificially, collections were begun early in July 
and continued until fall, for several seasons, the eggs being placed in 
hatching-jars at the Woods Hole Station ; all those collected prior to 
October 15 died. In November, 1895, 15,000,000 were placed in jars 
and carried through the winter under very unfavorable conditions, but 
hatched with a loss of only 50 per cent. The density of the water at 
Woods Hole varies from 1.023 to 1.025, its average temperature being 
from 49° to 64° during the months of April, May, and June. 

THE LOBSTER FRY. 

Owing to the cannibalistic habits of young lobsters when closely 
crowded, it has been the policy of the Commission to libera te the fry 
as soon after hatching as possible. They are taken out in ordinary 
10-gallon transportation cans, about 200,000 being placed in a can for 
short shipments and 125,000 for long shipments, and liberated in the 
vicinity of the grounds from which the adult lobsters were taken. 
When this is impracticable, they are liberated in Vineyard Sound and 
Buzzards Bay with an outgoing tide, so as to insure their wide distri- 



238 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 

bution. The question of the transportation of lobster fry any great 
distance is still an unsettled one, as in but few instances has it been 
attempted to ship them by rail, and then the trips were comparatively 
short — namely, from Woods Hole to Cold Spring Harbor, New York; 
from Woods Hole to Provincetown and Plymouth, and from Gloucester 
to Kittery Point. The shipments from Woods Hole have all been very 
successful, and there seems little doubt that the young lobster will 
stand transportation for 24 hours with excellent results. 



Report U S. F.C.I 897. 'To face page 239 ) 



Plate 62, 




THE TRANSPORTATION OF FISH AND FISH EGGS. 



During the earlier years of the Commission young fish were carried 
by messengers in baggage cars on regular passenger trains, but as the 
work increased it was found that this method was inadequate and that 
other arrangements must be made to transport the large numbers of 
fish which were being hatched. Accordingly, in 1879 and 1880, experi- 
ments were successfully made in moving shad fry in specially equipped 
baggage cars, and it was found that large numbers of fish could be 
economically moved with little loss. A car was therefore constructed 
specially adapted for the distribution of live fishes, the requirements 
of such a car being a compartment for carrying the fish in which an 
even temperature could be maintained, proper circulation of water and 
air in the vessels containing the fish, and sleeping and living accom- 
modations for the messengers attending them. 

A baggage car, the body of which was 51 feet long, 9 feet 10 inches 
wide, 13 feet 8 inches high, was purchased. At one end of the car was 
a room containing a stove, sink, and berth for the use of the cook, 
besides a boiler, pump, etc. ; and at the other were two sections of 
berths, like those in a Pullman car, which would accommodate two men 
on each side. Each compartment was about 7 feet long. In its center 
was a refrigerator compartment 30 feet 3 inches long by the full width 
of the car, and extending up to the clear story. The ice was carried in 
two racks, holding 1 ton each, which were located in the corners of the 
refrigerator, diagonally opposite each other. Cylinder cans, placed on 
galvanized iron tanks 9 feet 4 inches long, 28 inches wide, and 8 inches 
high, were provided in which to carry the fish. The tanks were placed 
on opposite sides of the car, with a passageway between them. 

An apparatus for circulating water was arranged in the following 
manner: In the top of the car, extending the full length of the clear 
story, was a long, semicircular iron tank 12 inches in diameter, which 
was filled through the top of the car. From this the water was brought 
into a 6 inch pipe extending all around the top of the refrigerator 
compartment. The pipe contained a sufficient number of pet cocks to 
supply the number of cans carried, the water being conveyed to the 
cans through rubber tubing. From the cans it passed into the tanks 
through the same-sized tubing, whence it was drained into 2-inch pipes 
underneath the car, and from these pipes was punrped up to the tank 
in the clear story. 

While this circulating apparatus worked well, its arrangement neces- 
sitated the carrying of a large amount of water in the top of the car, 

239 



240 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 

thus causing it to roll from side to side in such a manner as to make it 
unsafe. It was also found that while the refrigerator compartment 
carried the fish safely, the health of the messengers was injuriously 
affected owing to the sudden changes of temperature experienced in 
going to and from the compartment. Accordingly, another car was 
built in which these defects were remedied, and the original car was 
altered to conform to the improved plan. 

The Commission now has four transportation cars in use. While 
they differ somewhat in construction and arrangement, three of them 
are essentially alike; the fourth is simply a baggage car with living 
quarters and circulating apparatus. The car known as No. 2 is 
regarded as the best type. Its body is 52 feet 7 inches long; from 
buffer to buffer, 59 feet 9 inches; width, 10 feet; height, from top of 
rail to top of car, 14 feet 3 inches. It is equipped with 6-wheel Pull- 
man trucks, paper wheels, combination couplers, etc., so that it can be 
hauled on passenger trains. Underneath, between the trucks, are boxes 
for carrying provisions, tools, extra couplers, and a water-tank. Inside 
the car is finished in white ash, and due arrangements are made for the 
comfort and convenience of the crew. In one end is an office for the use 
of the captain, containing a sleeping-berth, desk, and toilet facilities; 
at the other end is the kitchen, with lockers for dishes, also the air- 
pump, steam-pump, and a 5-horsepower boiler for furnishing necessary 
power. 

The fish are carried in tanks or cans arranged in two refrigerator 
compartments on each side of the passageway. Over these compart- 
ments are two upper berths on each side for the accommodation of the 
crew, whose meals are served on a large table, placed when in use in 
the passageway in the center of the car. Chairs without legs are pro- 
vided, so that they can be placed on top of the refrigerators. 

The refrigerator-chambers are 26 inches high and 34 inches wide, and 
provided with lids; the partitions are filled with cork, which is used on 
account of its nonconducting properties. At one end of the chambers 
is an ice-box, which holds about three-fourths of a ton of ice. 

The transportation-tanks used in carrying yearling and adult fishes 
are made of heavy galvanized iron, and are 27 inches long, 27 inches 
wide, and 24 inches deep, holding 52 gallons each. They are heavily 
coated with asphalt before being used. 

For the transportation of fry ordinary 10-gallon iron cans, tinned, 
are used. These cans are 24 inches high, 12 inches in diameter on the 
outside, with sloping shoulders and cover, and two handles on the 
sides for convenience in moving. The water is introduced by means of 
a rubber hose connected with the pressure tank, or simply with a dipper 
or bucket. 

The supply of water is carried in an iron pressure-tank of 500-gallon 
capacity, which is located in the body of the car next to the office. The 
water is circulated by means of a steam-pump through galvanized-iron 



MANUAL OF FISH-CULTURE. 241 

piping, which runs from the pump to the pressure-tank, thence along 
the sides of the refrigerator to the transportation-tanks, whence it flows 
by gravity to a tank below the floor. From here it is pumped into the 
supply tank for redistribution. 

In order to provide sufficient air circulation, the air is driven by a 
pump to a 30-gallon reservoir in the top of the car over the boiler-room, 
from which it is taken to the transportation- tanks or cans through two 
lines of iron piping running along the sides and top of the car. One 
pet- cock is placed in the pipe for each tank to be supplied with air, 
which comes to it through a hole gV inch in diameter. From the pet-cock 
the air is carried into the tank with rubber hose and released in the 
water through liberators made of American linden, placed in hard- 
rubber holders. 

Before the present system of water circulation was adopted the water 
was taken from four 40-gallon tanks located in the bottom of the refrig- 
erator compartments, pumped into four 60-gallon supply-tanks, from 
which it flowed through the transportation-boxes and was returned 
thence to the lower tanks. The water supply was at first connected with 
a rotary hand-pump, and afterwards an arrangement was adopted to fur- 
nish power for the pump and an air-blower, by means of a friction wheel 
placed on the truck at one end of the car. This wheel was attached 
near one end to the top of the truck, so that it rested on the tread of 
the car wheel and was held there by two spiral springs. When not in 
use, it could be elevated above the car wheel by a lever operated from 
inside the car. Power was transmitted from the friction wheel by means 
of a countershaft and rubber belting. The friction wheel gave a great 
deal of trouble, however, as it was impossible to make it strong enough 
to stand the wear to which it was subjected. As the action of the truck 
springs, while the car was in motion, moved the truck frame up and 
down — sometimes 3 to 5 inches — the friction wheel would be jolted out 
of position, and so uncertain was its operation that it could not be relied 
upon and the pump and blower had to be worked by hand. 

This car is also fitted up with a hatching outfit, consisting of eight 
lead-lined boxes about 6 inches high, which may be placed on top of 
the refrigerators and made to fit in place of the lids, which can be 
removed. These boxes each hold six McDonald jars. An aquarium, 
specially made for the work, is placed in the center of each box, with 
three jars on each side of it. The jars and aquarium are securely 
wedged in the box, so that they can not move. The supply of water for 
the jars comes from the supply-pipes in the refrigerator compartments, 
the pipe coming up through the top of the refrigerator near the center, 
then branching out on each side with pet-cocks in it, to which is 
attached the rubber tubing to supply the jars. The overflow is through 
a pipe leading out of the bottom of the boxes into the tank under the 
car. 

Fry are carried in cans, and yearlings and adults in the transporta- 
tion tanks. Great care is taken not to make a sudden change in the 

F. C. K. 1897 16 



242 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 

temperature. If the air and water circulations are not used it is neces- 
sary to aerate the water with a dipper, that is, to take a dipperful of 
water from the can and, holding it up about 2 feet, pour it back, thus 
taking air with the water to the bottom of the can. This is done as 
often as is necessary to keep the water fresh. 

Whitefish fry are carried in water at a temperature from 33° to 45° F. 
If necessary to reduce the temperature, ice can be placed in the water 
with the fry. If the air. and water circulations are used, about 40,000 
fry can be carried in each can. Without the circulation 20,000 are 
carried, and in order to aerate them it is necessary to draw off in a pail, 
through a screened siphon, about one-half the water in the can. This 
is then thoroughly aerated in the pail with a dipper and returned to 
the can, with a small amount of fresh water added. When a car arrives 
at its destination, the cans are taken to a tugboat or steamer and 
carried to the spawning- grounds where the whitefish are to be planted, 
by carefully lowering the cans into the water and allowing the fry to 
escape. On board the boat they are given fresh water as fast as is 
required to keep them alive. 

Shad fry are carried in water at a temperature of from 55° to 65°, 
depending on the temperature of the water in which they were 
hatched. These fry can not be carried successfully with the circu- 
lating system of water or air, and aeration, by the use of the dipper, is 
therefore necessary. From 20,000 to 30,000 are carried in each can. 
When the water is to be changed, it is drawn off through a siphon into 
a pail, the head of the siphon being in a wire cage, covered with 
cheese-cloth to prevent the fry from escaping. After the water in 
the pail has been thoroughly aerated and ice added to bring the tem- 
perature down to what is required, it is poured back through a large 
funnel which reaches nearly to the bottom of the can. To prevent the 
force of the water from injuring the delicate fry, the lower part of the 
funnel for about 6 inches is made of perforated tin. When long trips 
are made, the sediment which collects on the bottom of the cans is 
removed, as soon as it is noticed, by drawing it off through a siphon into 
a pail. Should any fry come out with it, they are carefully returned 
to the can by dipping them out after the sediment has settled to the 
bottom of the pail. If a trip lasts five or six days, the cans are cleaned 
every other day by transferring the fry with a dipper from one can to 
the other and cleaning the empty one before the fry are returned to it. 
Shad fry are more tender than any other young fish moved on the cars, 
and the greatest care is necessary in handling them. 

Trout and salmon fry are carried in water at a temperature of 36° to 
46°, though rainbow trout are sometimes transported in water 10° or 
15° warmer. If it is necessary to reduce the temperature, ice is placed 
in the cans with the fish. Each can contains 5,000 trout fry, and 2,000 
to 3,000 salmon fry, when the air and water circulations are used; 
without air circulation, 3,000 or 4,000 trout, and 1,200 to 1,500 salmon 



MANUAL OF FISH-CULTURE. 243 

fry are allowed to each can — the number depending on the length of 
the trip and age of the fry. These fish are moved as soon as the sacs 
are absorbed, or when they first begin to swim up from the bottom. If 
shipped before this period of life, they are liable to collect on the center 
of the can in the bottom and smother. If the fry will keep away from 
the mouth of the can, the water is aerated by dipping it directly from 
the can and letting it fall back; but if the fish do not go down when 
the dipper is introduced, the water is siphoned into a pail, aerated, and 
then poured back. 

Small yearling trout are sometimes carried in cans, but usually in 
the galvanized-iron tanks; 100 to 200 are put in each can if the air 
circulation is used, and the water is kept cool by introducing ice. As 
salmon and lake trout are more delicate than the others, the number 
placed in each can is reduced. When shipping adult trout but few can 
be taken in each tank, only from 20 to 50 if they are of large size. 
They are given all the air and water circulation possible and carried at 
a low temperature. Incessant watchfulness is necessary in moving 
these fish. When the fish are in distress they come to the surface of 
the water, and if the water is then vigorously aerated they will return 
to the bottom of the tank. 

When black bass are distributed in the fry stage they should be 
shipped in water from 40° to 60° F., according to the temperature «of 
the water from which they are taken; but it is considered preferable 
to hold these fish in the ponds or feeding-troughs until they are from 
three to six months old, when they will have attained a length of from 
1£ to 3 or 4 inches, fish hatched at the same time often varying consid- 
erably in length. These older fish also require a temperature of from 
40° to 60°, according to circumstances, when they are transported. 
Young black bass are very voracious, and begin to eat each other as 
soon as they are confined in cans or tanks for transportation. The 
number of bass carried in each tank is approximately as follows: Fifty 
8 to 12 inches long; one hundred and twenty 5 to 8 inches long; two 
hundred and fifty 2 to 5 inches long. 

Crappie are carried in the same manner as black bass, although it 
is more difficult to handle them. Eock bass are commonly carried in 
cans, about 500 to 700 in each if the fish are about an inch long. The 
temperature of the water is from 40° to 60°. 

Codfish fry are moved in cans with water of a temperature of 33° to 
38°. The trips are usually of short duration. The water is aerated 
by drawing it from the can through a screen siphon into a pail and 
returning it after it has been thoroughly aerated. 

Large lobsters, on long trips, are packed in seaweed in wooden trays 
about 6 inches high and of a size convenient for handling. Strips of 
wood attached to the bottom of trays have open spaces between them 
to allow air circulation. About 2 inches of seaweed are spread on the 
bottom of the tray and the lobsters placed on it with their claws 



244 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 

toward the outer ends, so that they can not injure each other, and the 
trays are then filled with seaweed. They are packed in the refriger- 
ator compartments, and the temperature of the air is kept, if possible, 
at from 40° to 48° F. A supply of salt water, filtered through cotton, 
is taken along, and the lobsters are sprinkled with it three or four 
times a day, and they are also daily overhauled and repacked. If the 
desired temperature is maintained, 50 to 60 per cent can be carried 
for five or six days. Lobster fry are moved in the same manner as 
codfish fry. 

In transporting adult salt water fishes, as many as possible are 
placed in the tanks without overcrowding them. The water is kept 
fresh by air circulation only. Ice is packed around the galvanized iron 
tanks to keep them cool, and if necessary to reduce the temperature a 
can filled with ice is placed in the water. Marine fishes have been 
transported successfully for 6 days or more. 

A large number of fish are distributed yearly by messengers, acting 
independently of the cars. Each messenger is supplied with a sufficient 
number of 10-gallon cans, and is equipped with a dipper, a 5 gallon 
iron pail, a large tin funnel with a perforated bottom, a thermometer, 
and a piece of f -inch rubber hose, about 4 feet long, for use as a siphon, 
besides a supply of ice. 

When it is necessary to renew the supply of water, the messenger 
sees that it is clean, fresh, free from lime, iron, and other deleterious 
substances. Especial attention must be given to this in passing 
through limestone regions, and fresh water must be tested before the 
supply on hand is thrown away. The fry are cared for and aerated in 
the same manner as has been already described for transporting them 
in cans. 



SPAWNING SEASONS OF FISHES PROPAGATED, CHARACTER 
OF FISH EGGS, PERIOD OF INCUBATION, ETC. 



In the following table there are presented, in a form convenient for 
reference, some of the more important facts connected with eggs of the 
fishes artificially cultivated in the United States. It should be under- 
stood that there is considerable variation in many of the items, depend- 
ing on climatic conditions, size and age of fish, etc. } the information for 
such can therefore be only approximately correct. For certain of the 
less important fishes, it is possible, from the data available, to supply 
only a part of the information indicated by the column headings. The 
spawning season given is generally that of wild fish in the regions where 
fish-cultural work is prosecuted; this varies much with latitude and 
local conditions. 

Fish eggs, as regards their physical characters, naturally fall into 
four classes, as follows : 

(1) Buoyant or floating, as the eggs of the cod, mackerel, and most 
pelagic fishes, which come to the surface when first deposited and 
remain there during at least the early stages of incubation. 

(2) Semi-buoyant, as the eggs of the shad and whiten sh, whose spe- 
cific gravity is but slightly greater than that of water. 

(3) Heavy, non-adhesive, as the eggs of salmon and trout. 

(4) Heavy, adhesive or glutinous, as the eggs of the flatfish, sea her- 
ring, yellow, perch, and most pond fishes. 

The differences in the types of hatching apparatus depend primarily 
on the foregoing characters of the eggs. 

At the hatching stations the size of eggs is determined by placing a 
number of moist eggs, shortly after taking, on a flat surface, side by 
side, and noting how many are required to cover a linear inch. Owing 
to capillary attraction between adjoining eggs leading to compression 
or flattening of the contiguous sides, this method is liable to slight 
error, the extent of which is in inverse proportion to the size of the 
eggs. 

By means of the microscope, accurate measurements of small eggs may 
be made. The size of eggs of a given species often varies considerably, 
sometimes amounting to 25 per cent. 

245 



246 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 



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NOTES ON THE EDIBLE FROGS OF THE UNITED STATES 
AND THEIR ARTIFICIAL PROPAGATION. 



F. M. CHAMBERLAIN, 

Assistant, U. S. Fish Commission. 



249 



NOTES ON THE EDIBLE FROGS OF THE UNITED STATES AND 
THEIR ARTIFICIAL PROPAGATION. 



The frogs are familiar representatives of the great class of cold- 
blooded vertebrates known as the Batrachia. The batrachians are 
intermediate anatomically and physiologically between the fishes and 
the reptiles (snakes, turtles, terrapins, alligators, etc.); they are chiefly 
characterized by the metamorphosis which the young undergo before 
assuming the functions and habits of the adults. The young are mostly 
aquatic and breathe by means of gills, which absorb oxygen from the 
water. Later the gills disappear and are replaced by lungs. 

The frogs are included in the order Salientia (the leapers), distin- 
guished by having a short, depressed body and four limbs, the hind 
pair being much enlarged and adapted to leaping and swimming; the 
tail, present in the young, disappears with age. In the related orders 
(Urodela, containing the salamanders and newts; Proteida, the mud- 
puppies or water-dogs, and Traehystomata, the sirens or mud-eels) the 
tail persists in adult life and the hind limbs are small, but the metamor- 
phoses and habits otherwise more or less closely resemble the Salientia. 

Associated with the frogs (Banidw), in the order Salientia, are the 
families (Bufonidce and Hylidw) to which the toads and tree frogs 
belong. The toads are very closely related to the frogs, but differ in 
having more terrestrial habits and, among other structural features, in 
the absence of teeth and the possession of an expansible thorax ; their 
uncouth form and the x>ungent secretions which have brought them 
immunity from the attacks of other animals have added to the preju- 
dice against their relatives, the frogs. The tree frogs are characterized 
by arboreal habits and corresponding changes in structure. More than 
250 species of true frogs (Banidce) are known. They are most numer- 
ous in Africa and the Bast Indies. 

The edible frogs of the United States belong to the genus Bana 
(Latin, a frog). Of these, Professor Cope in his Batrachia of North 
America (1889) lists 13 species and 6 subspecies or varieties, to which 
there have since been some additions. 

POOD VALUE OF FKOGS. 

The value of frogs as food is now thoroughly recognized. The meat 
is white, delicate, and very wholesome and palatable. Although eaten 
at all times, it is in best condition in fall and winter; in spring it is of 

251 



252 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 

relatively inferior quality. Only the hind legs are commonly utilized, 
the meat on the other parts of the body being edible, but in very small 
quantity. In some localities, however, the entire body, after the removal 
of the viscera, is fried with eggs and bread crumbs. The legs are pre- 
pared for the table by broiling, frying, or stewing. 

A prejudice formerly existed against frogs as an article of food, per- 
haps based on their uncanny appearance and heightened through their 
appropriation by witches and empirics for spells in love affairs and the 
cure of various diseases. For a long time the French people alone 
availed themselves of this delicacy, though it was known to the Romans. 
From France the use of this food passed into Germany, England, and 
other parts of Europe, and later into the United States, where frogs 
are now more generally consumed than in any other country, and 
where, during the proper seasons, they may be found in the markets 
of any of the larger cities.* 

FROG-HUNTING. 

The business of taking frogs for market has greatly increased in 
recent years. It is now carried on in all sections of the United States, 
and is of economic importance in about fifteen States, while in nearly 
all the remaining States and Territories frogs are taken for local or 
home consumption, of which it is impossible to get a statistical account. 
The States supplying the largest quantities for the markets are Cali- 
fornia, Missouri, New York, Arkansas, Maryland, Virginia, Ohio, and 
Indiana. More frogs are taken in New York than in any other State, 
but on account of their comparatively small size their value is less than 
in Missouri and California. The Canadian Province of Ontario also 
yields a comparatively large supply of market frogs. According to 
inquiries of the United States Fish Commission, tiie annual catch in 
the United States is but little less than 1,000,000, with a gross value to 
the hunters of about $50,000. The yearly cost of frogs and frog legs 
to the consumers is not less than $150,000. 

The localities in which especially important frog hunting is done are 
the marshes of the western end of Lake Erie, and Lewis and Grand 
reservoirs, in Ohio; the marshes of the Sacramento and San Joaquin 
rivers, California; the valley of the Kankakee River, Indiana; Oneida 
Lake, Seneca River, and other waters of northern New York, and the 
St. Francis River and the sunken lands of the Mississippi River, in 
Arkansas and Missouri. 

In taking frogs for market, lines baited with red cloth, worms, or 
insects are extensively used; guns, small-bore rifles, and spears are 
also employed, and cross-bows are adopted for this purpose in Canada. 
They are often hunted at night, a lantern furnishing light for the 

* While it is popularly supposed that the consumption of frogs in France is much 
larger than elsewhere, this is not the case, and, on the authority of the Revue des 
Sciences Naturelles Appliquees (1889), it may be stated that the annual consumption 
of frogs in the United States is ten times that in France. 



MANUAL OF FISH-CULTURE. '253 

hunter's aim, and at the same time blinding or dazing the frogs. After 
entering on their hibernation, many are dug out of the mud, large 
numbers often being found together at this time. 

In the basin of the St. Francis Biver, in Missouri and Arkansas, where 
the business is important, frogs are captured by means of spears, with 
lines at the end of long rods, and with firearms. In the early part of 
the season, when the frogs retire to the mud during the cool nights, and 
only appear on warm, bright days, they are taken on hooks baited with 
red cloth and by guns and rifles. Later the bulk of the catch is made 
at night by means of spears with one to three barbed prongs. Two men 
usually hunt together in a boat, one rowing, the other standing in the bow 
with spear and a large reflector made especially for the purpose. The 
season in this region is principally from March to June. Only the hind 
legs are preserved ; a pair of these weighs about half a pound. 

The prices received for frogs varies greatly, and depends on the con- 
dition of the market, the size of the frogs, and the locality. Dressed 
legs yield the hunters from 12£ to 50 cents a pound, and live frogs 
from 5 cents to $4 a dozen. In the Kankakee Valley, Indiana, for 
example, the prices received by the hunters are 75 cents a dozen for 
large frogs, 10 cents a dozen for medium-sized frogs, and 5 cents a 
dozen for small frogs, while in San Francisco the market price is $3 to 
$4 a dozen. 

The unrestricted hunting of frogs threatens their practical extinction 
iu all places where their abundance and shipping facilities or proximity 
to market render the business profitable. Already a marked decrease 
iu the supply is manifest in Lake Erie, in northern New York, and 
other places, and in order to meet the increasing demand hundreds of 
people are experimenting or preparing to engage in frog-culture. 

The need of definite information as to the methods of procedure has 
been generally felt and frequent inquiries concerning frog-culture are 
received by the United States Fish Commission. While the practica- 
bility of artificial propagation has not been demonstrated, it is evident 
that the number of salable frogs from a given area may be largely 
increased by artificial means. To undertake intelligent work in this 
line a knowledge of the natural history of the frog is essential. 

HABITS AND DEVELOPMENT OF FROGS. 

All frogs undergo a tadpole stage, though in some species this is so 
rapid as to lead the casual observer to think it omitted. 

Upon the disappearance of frosts at the close of winter the hibernating 
frogs return to active life, and as the waters become warmer in the spring 
sun their notes are heard in suitable localities all over the country. 
In some species the song is distinctly a chant d 7 amour; in others it is 
continued long after the breeding season is over. During the breeding 
season the social instinct prevails, and species of usually solitary habits 
congregate in large numbers, thus becoming ready prey for the hunter. 



254 REPORT 01' COMMISSIONER OF FISH AND FISHERIES. 

The eggs are extruded by the female and are fertilized by the male 
as they pass out, very few failing to be impregnated. The process of 
oviposition or laying continues through several days, and during this 
period several hundred eggs may be deposited. The size of the ova 
varies with the species, but averages about 1.75 millimeters (.07 inch) 
in diameter. In passing down the oviduct the egg receives a thin 
coating of albuminous material ; this rapidly swells when the egg enters 
the water and forms the well-known gelatinous mass in which the frog 
eggs are always found imbedded. The toad's eggs are laid in long 
strings and are readily distinguishable. The salamander's eggs are also 
placed in the water, but the gelatinous mass is somewhat firmer and 
the eggs are slightly larger than the frog's, and they are usually 
deposited somewhat earlier. 

The eggs begin development, under favorable circumstances, as soon 
as fertilized, the rapidity depending mainly on the temperature of the 
water ; incubation is much retarded by cold, and some seasons many 
eggs are killed by late frosts. At first the upper part of the eggs is 
black and the lower white, but the rapid growth of the black embryo 
makes the entire egg dark. The egg, which is at first spherical, soon 
becomes ovoid. In from 4 to 30 days the tadpole is able to wriggle 
out of its gelatinous envelope and shortly attaches itself to some plant 
or other support by means of a sort of adhesive organ in front of the 
mouth. At first the mouth and anus are closed, and food can only be 
obtained by absorption, the first food consisting of the gelatinous egg- 
envelope. In a short time the mouth and anus become functional, the 
alimentary canal lengthens, and macerated animal and vegetable matter 
becomes the food. The prevalent idea that the tadpole is exclusively 
vegetarian, based on its anatomical structure, horny jaws, and long 
intestine, is incorrect. Recent observations have shown that animal 
matter is preferred to vegetable ; all food must be in a state of macera- 
tion, especial fondness for dead animals being shown. 

Respiration is at first carried on by means of external gills. They 
are soon replaced by internal structures covered by opercula. 

Rapidity of development depends upon the abundance of food and 
the temperature of water. The most favorable conditions are a shallow 
pool, readily warmed by the sun and well stocked with organic matter, 
that is, an old pond. In this stage the frogs may reach a length of 
several inches, the bullfrog tadpole being largest. The various species 
closely resemble each other, but can be distinguished after some expe- 
rience by certain points of mouth structure, size, and coloration. 

In a period varying from two months to two years the first indication 
of the adult form appears in the protrusion of the two hind legs. The 
forelegs or arms, owing to their being concealed by the gill membranes, 
are much later in coming out. 

As the legs become functional the tail is absorbed and furnishes 
material for growth, so that little food is taken. In the case of the 
second-year tadpole the capture of insects is begun before the tall is 






MANUAL OF FISH-CULTURE. 



255 



lost. As the gills are replaced by lungs during this period, it is essen- 
tial that the tadpoles have access to land or resting-places, and it is a 
time of peculiar difficulty in the creature's existence. When the tail 
is almost fully resorbed, the purely aquatic life is forsaken for the 
amphibious and the food is changed from dead to living matter, which 
must demonstrate its living condition by motion. The peculiarly formed 
tongue — loose behind, so that it may be thrown out to quite a distance — 
is covered with a viscid secretion so that the frog readily captures 
any insects or small animals that approach it closely. Tadpoles are 
commonly satisfied to wait patiently for their food, and even the adults 
do not often search actively for food. Sexual maturity is reached in 
about three or four years, being latest for those varieties that pass the 
first winter in the tadpole stage. It is generally believed that frogs 
live for 12, 15, or even 20 years. 

During the tadpole stage they furnish tempting morsels for fish, rep- 
tiles, some mammals, and other frogs, and especially for wading birds, 
like herons and cranes. Their defenseless condition and the shallow- 
ness of their natural habitats at this period make them ready prey, 




Spring Frog or Leopard Frog (Bana vireseens). 

and it is in the prevention of this wholesale destruction that m 
profitably intervene. In the adult frog stage the relent uit by 

birds and reptiles is continued until of the hundreds of eggs deposited 
few become reproducing individuals. Only slight revenge for all this 
slaughter can be taken. They may occasion! ally capture disabled fish 
or small fish of sluggish habits found in he id or on the bottom, and 
instances are recorded of their eating ' , toads, and young birds, 
but insects and lower forms are then i diet. 

DESCRIPTIONS OF MARKETABLE FROGS OF THE UNITED STATES. 

The species of frogs comit'm; eaten are the bullfrog {Bana cates- 
biana), the green frog (Rana dampta), the spring frog (Bana vireseens), 
and the western bullfrogs [Bajna pretiosa and Bana aurora). 

The following references to their geographical distribution and brief 
descriptions of their color a nd form have mainly been extracted from 
Professor Cope's work on 'The Batrachia of North America (Bulletin 
No. 34, U. S. National Muffeam, 1889). 



256 REPORT OF COMMISSIONER OF FISH AND FISHERIES. - 

The most widely distributed species is the common frog, spring frog, 
shad frog, or "leopard frog (Bana virescens). It is found from the 
Atlantic Coast to the Sierra Nevada Mountains, and from Lake Atha- 
basca, in Canada, to Guatemala, Central America, but is most abundant 
in the Eastern States. It reaches a length of about 3£ inches, exclusive 
of legs. The toes are well webbed, but the web does not reach the 
tips of the fourth toe, as in the common bullfrog. The head is moderate 
in size, the snout being rather pointed; the tympanum (ear) is distinct 
and nearly as large as the eye. The hind limb being carried forward 
along the body, the tibio-tarsal articulation reaches nearly the tip of 
the snout. The color is usually bright green, marked by irregular black, 
dark-brown, or olive blotches edged with whitish or yellowish. These 
spots form two irregular rows on the back and one or two more or less 




Green Frog or Spring Frog (Bana clamata). 

indefinite rows 01 aid The blotching is continued as spots or bars 

on the posterior extr amities. These spots are frequently smaller and 
more numerous than shown in the specimen figured. The glandular 
fold Avhich runs from the orbit to the posterior part of the body is 
yellow. The under surface uitish or light yellow and unspotted. 

The leopard frog passes the ta< j . stage the first season, and is more 
gregarious than the bullfrog oi ben frog. These considerations are 
of importance from a culturist's g andpoint. 

The green frog or spring frog (Bana damata) is found throughout the 
Eastern and Central States and neighboring parts of Canada. The 
body and limbs are stout and massive, tl e legs are short, and the head 
is more rounded than in B. virescens. ' » tympanum is very large, 
though this differs in the sexes, as a rule ; eing larger than the eye in 



MANUAL OF FISH-CULTURE. 



257 



males and smaller in females. A fold of skin runs from the eye back- 
ward, with a short branch from the tympanum to the shoulder. The 
femur and tibia are equal in length, the web of toes not reaching end 
of fourth toe. 

The color above is dark olive posteriorly, passing into brilliant green 
anteriorly. It is sometimes greenish-brown above and on sides, with 
small round brown spots. The buttocks are usually mottled with brown 
and yellowish white, but are almost uniformly black in some specimens. 
Below, this species, white or greenish white, sometimes more or less 
mottled and blotched. The throat is citron yellow. 

This frog is especially aquatic in habits, not hunting on land; it fre- 
quents all kinds of fresh waters. It is more solitary in its habits than 
R. virescens, living singly, in pairs, or in small companies. It is active 
on land and in water, but not noisy. A nasal "chung" is occasionally 
uttered. When disturbed it often emits a shrill cry as it leaps into 





Rana catetbiana. "Upper fig- 
ure female, lower fiaure male. 



Rana clamata. Upper figure fe- 
male, lower figure male. 



Figures illustrating relative size of the tympanum in the two sexes. 

the water. It is preeminently an inhabitant of swamps and marshes, 
especially those connected with rivers or large creeks. "It is the first 
species heard in spring, and although its voice is not loud, the noise 
produced by thousands of them is deafening when heard close at hand, 
and is transmitted through the atmosphere for many miles. It may be 
imitated by the syllables chock, chock, chock. 1 '' 

Tbe pickerel frog, marsh frog, or tiger frog {Rana palustris) closely 
resembles the leopard frog, but may be readily distinguished from it by 
the bright yellow on tbe thighs and legs. It is solitary in its habits 
and is often found in the grass, although preferring cold spring streams. 
In the Alleghany Mountains it is the most abundant frog. It is a very 
active species, taking longer leaps than any of the others here mentioned. 
The note is a prolonged, low, grating croak. Owing to its disagreeable 
odor it is but rarely eaten. 

F. C. B. 1897 17 



258 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 

The bullfrog (Bana catesbiana) is the largest of North American 
frogs, reaching a body length of over 8 inches. It has much the same 
geographical range as the spring frog. The body is very bulky and 
clumsy ? the legs are thick, and the head is broader than in B. clamata. 
A fold of skin extends from the eyes over the tympanum, around the 
insertion of forearm, and disappears on the breast. There are no folds 
on the sides of back, as in B. clamata and B. virescens. The skin is 
slightly rough above. The tympanum is larger than eye, with the same 
sexual differences as in B. clamata. The tibia is slightly shorter than 
the femur. The hind toes are fully webbed. The complete webbing of 
the fourth toe, with the absence of dorsal folds of skin, furnishes means 
of distinguishing this from the spring frog. 




Common Bullfrog (Bana catesbiana). Male. 

The color above is olivaceous, brown, or ferruginous, with darker 
blotches half the diameter of the eye, more or less uniformly distributed. 
The color is sometimes yellowish green without blotches or other mark- 
ings. The hind legs are barred above and the buttocks blotched with 
nearly black markings. The lower parts are white, with obscure 
mottlings of brown, the throat sometimes being bright yellow. In the 
young the blotches above are reduced to distinct black dots, and the 
under parts are yellowish anteriorly. The habits are much the same as 
those of B. clamata. Both species pass the first winter in the tadpole 
stage and are said under unfavorable circumstances to pass even the 
second winter so. This fact, with the solitary habits of the adult, is of 
importance to the culturist. 

"The Western frogs are not well known. The range of Bana pretiosa 
is from Montana west to Puget Sound, thence south to southern Cali- 
fornia. It is the common frog of the Northwestern States. The body 
is stout and depressed like B. catesbiana. The head is obtuse, rounded, 
subtruncate, and broader than long. The eyes are small and the 



MANUAL OF FISH-CULTURE. 



259 



tympanum, which is sometimes indistinct in some small specimens, is 
smaller than the eye. Skin thick. The femur is shorter than the tibia 
and not quite half length of body. The toes are fully webbed. A 
depressed ridge extends from eye to flank. The color is dull yellowish- 




Western Frog (Bana pretiosa). 

brown (dead leaf) above, darker on sides, with circular brown blotches 
between the ridges. The outer surface of the limbs is blotched trans- 
versely. The body spots are often less numerous and smaller than in 
the specimen figured. The under parts are yellowish white, with obscure 
brown marbling, posteriorly salmon color. 




Western Bullfrog (Bana aurora). 

Bana aurora is found in the western coast region of the United States. 
The body is depressed and elongated ; limbs slender, well developed; 
head broad, acute, rounded anteriorly; eye moderate; tympanum 
smaller than eye, but not so small as in preceding species. A fold of 



260 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 

skin runs from eye to hind leg. The femur is shorter than the tibia, 
which is rather more than half the length of body. The toes are not 
quite fully webbed, the last joints of all the toes and last two of the 
fourth toe being free. The color above is greenish-yellow, with golden 
reflections, spotted with black. The sides of abdomen aud hind legs 
are reddish-orange. The under parts are dull yellowish-green, spotted. 
While the species of frogs described are those commonly used for 
food, there seems no valid reason why any of the Banidce may not be 
eaten. The small size of some, with possibly a disagreeable odor, has 
prevented their use up to this time. 

SUGGESTIONS FOR FROG-CULTURE. 

From the foregoing discussion of the development of the frog it will 
be seen that its culture mast be of necessity a matter requiring time, 
patience, and an appreciation of the animal's habits and needs. So 
far as can be learned, attempts thus far made in the cultivation of 
frogs from the egg stage have been arrested at the period when the 
larva assumes the adult form. From this time the food must be living, 
and it generally consists almost entirely of insects. The difficulty, 
approaching impossibility, of furnishing these in sufficient quantity 
has been the great drawback. The placing about the pond of meat 
and decaying matter to attract flies has been suggested, but the con- 
tamination of the water by the i)oisonous matters of decomposition has 
counteracted all benefits produced. The frogs, failing in the supply of 
more natural food, have been compelled to devour one another. 

To rear the tadpole is comparatively easy. Anyone may obtain a 
supply of eggs by visiting the stagnant pools in early spring with a 
dipper and bucket, but this method is said to be less advantageous 
than the stocking of suitable waters with a sufficient number of pairs 
of mature frogs. The young can be protected by building a close fence 
around the edge of the pond to exclude such enemies as raccoons and 
reptiles, while a screen must be provided so that wading birds, whose 
long legs furnish them special facilities, can not stand in the water and 
devour the helpless tadpoles. Any device to be effective must be so 
arranged that there is no room for birds or other animals to stand on 
shore or in shallow water, either on or under the screen, and at the 
same time it must allow the young to come to land, for if there is no 
opportunity for the tadpoles to breathe the air at rest and exercise the 
legs, the period of metamorphosis will be indefinitely delayed. They 
have been kept in aquaria for years in the tadpole stage. 

Food during this period is readily provided. If a shallow old pond 
is chosen, already well stocked with organic matter, it will supply, un 
aided, food for a large number of frogs. This may be readily increased 
by supplying animal refuse, liver and such material, care being taken, 
of course, not to leave a surplus to putrefy and infect the water. The 
more abundant the food and the warmer the water the more rapid is the 



MANUAL OF FISH-CULTURE. 261 

growth, hence the desirability of selecting a shallow pond. The young 
should be separated from the adult frogs during this time, as they are 
eagerly eaten ; and it is needless to say that the pond must be free 
from fish, turtles, snakes, and crayfish. 

The critical period occurs at the time of metamorphosis. The crea- 
ture is now abandoning its aquatic habits and has not yet a perfect 
apparatus for terrestrial life. Any slight disarrangement of the natural 
environment is liable to destroy the equilibrium. The rapid resorption 
of the tail furnishes matter for growth, so that food is not so much a 
necessity, but as soon as the terrestrial habit is fully assumed live food 
is absolutely requisite, and should be furnished in liberal quantities. 
There seems to be no reason why this might not be accomplished by 
transfer of the tadpoles to waters where natural food abounds. It is 
useless to attempt to supply this food artificially by any method at 
present known, neither has any device to increase the natural abundance 
of insects been practicable as yet. The pond should have a growth 
of rushes and other plants; wild rice (Zizania aquatica) has been recom- 
mended, but it might attract birds that would prefer young frogs and 
tadpoles to their vegetable fare. Shade is necessary. Such a pond 
will furnish natural food for a large stock of frogs, and give opportunity 
for successful breeding. 

One of the most successful " frog farms " is in Ontario, in the Trent 
River basin. It has been in operation about twenty years and annually 
yields a comparatively large product of frogs. The waters were stocked 
by means of mature mated frogs. No attempt is made to confine the 
frogs until near the time for shipment to market. They are then taken 
alive at night, with the aid of a torchlight, and confined in small pens 
that can be drained when the frogs are desired for market. No food is 
given, as this is naturally present in sufficient amount for successful 
growth. The species is the eastern bullfrog (Bana catesbiana) ; it 
begins to breed at the age of three years and reaches a marketable size 
in four years. During the years 1895 and 1896 this "farm" yielded 
5,000 pounds of dressed frog legs and 7,000 living frogs for scientific 
purposes and for stocking other waters. 

While at present it would perhaps be advisable to limit practical 
attempts at frog-culture to stocking natural waters with paired breeders, 
experiments in artificial methods should not be abandoned. There 
seems no reason why methods similar to those at present pursued in 
fish-culture may not eventually be successful in the case of frogs. 



OYSTERS AND METHODS OF OYSTER-CULTURE. 



H. F. MOORE, 

Assistant, U. S. Fish Commission. 



263 



CONTENTS. 



Introduction 265 

Distribution: 

Atlantic coast 265 

Pacific coast 266 

Description : 

Eastern oyster, Ostrea virginiana 266 

Pacific coast " native, " Ostrea lurida. 267 

Reproduction and development : 

Sexual characteristics 267 

Ripening of the generative organs. . . 268 

Spawning 268 

Embryonic development 270 

Fixation, set, or spatting 274 

Growth 274 

Anatomy 276 

Physical and biological conditions on oys- 
ter-beds : 

Temperature of water 280 

Temperature; planted beds in San 

Francisco Bay .* 281 

Density of water; determination of 

density and temperature 281 

Silt, mud, and suspended matter 283 

Tides and currents 284 

Depth of water 285 

Weather conditions — storms, gales, 

and ice 285 

Food 286 

Enemies 288 

264 



Description of natural bed 292 

Destruction of natural beds — causes and 

remedies 295 

Increase of supply by artificial means 296 

Planting with seed : 

Preliminary considerations 298 

Preparing bottom 299 

Seed 301 

Sowing the seed 302 

Working the beds 303 

Planting with cultch or stool : 

Preliminary considerations 304 

Preparing bottom 305 

Cultch, collectors, stool 305 

Coating cultch 309 

General considerations on spat-col- 
lecting 310 

Working the beds 312 

Protection from enemies 313 

Increase on planted beds 320 

Growing oysters in ponds 320 

Breeding oysters in ponds 322 

Artificial propagation 330 

Artificial feeding 335 

Fattening, plumping, floating 336 

Greening 337 

Transportation and length of life when 

removed from the water 338 

Notes on clam-culture 339 



OYSTEES AND METHODS OF OYSTEE-CULTUEE. 



By H. F. Moore, 

Assistant, United States Fish Commission. 



INTRODUCTION. 

This paper is designed to briefly set forth the principal facts relating 
to the subject of oyster- culture in the United States. It embraces the 
practices of proved commercial value as well as a summary of the 
methods and results of investigations which appear to give some prom- 
ise of utility in certain places and under special conditions, or which 
indicate the lines along which profitable experiment may be carried on. 
It is intended primarily as a guide to those persons who are exhibiting 
an interest in the subject and who contemplate embarking in the 
industry, yet hesitate on account of unfamiliarity with the methods 
employed. To aid such persons to a more thorough understanding of 
the problem involved, certain matters are considered which do not 
strictly appertain to the practical side of the subject, but which may 
assist in explaining observed phenomena or in indicating the lim- 
itations and possibilities of experiment. Such are the chapters on 
development and anatomy. 

Attention is directed chiefly to the eastern oyster, which is the species 
of principal, one might almost say only, interest in this country, and, 
practically, the great problem of oyster-culture applies to it alone. 
For comparative purposes, however, and to round out the information 
presented, it has seemed advisable to incorporate some facts regarding 
the native oysters of the Pacific Coast. 

DISTRIBUTION. 
ATLANTIC COAST. 

Upon the eastern coast of North America there is but one species of 
oyster, Ostrea virginiana, which occurs along the northern side of the 
Gulf of Mexico, on the Atlantic coast from Florida to Cape Cod, and on 
the southern and western shores of the Gulf of St. Lawrence. In 
Massachusetts Bay and on the coast of New Hampshire and Maine it 
does not now occur, though it was found in abundance locally at the 
time of the settlement of the country, and the former existence of beds 
of great extent is indicated by the vast quantities of the valves in the 
ancient Indian shell-heaps. Oyster fisheries are located in every coast- 
wise State from Texas to Massachusetts and in the Maritime Provinces, 

265 



266 REPORT OF COMMISSIONER OP FISH AND FISHERIES. 

the most important being in Chesapeake Bay, mainly upon the natural 
beds, and in Long Island Sound, principally upon planted grounds. 
The Canadian oyster-beds are much depleted, and an effort is now 
being made to restore them to a productive condition. 

PACIFIC COAST. 

Upon the western coast of North America there are five, and perhaps 
six, recognized species of oysters, but only two of them are of present 
importance. 

The eastern oyster was planted in San Francisco Bay about 1872 and 
has there formed the basis of a somewhat important industry ever 
since. The supply has been maintained by the annual planting of seed 
oysters from the east, and while the species appears to be propagating 
itself to a limited extent, no reliance has been placed upon this fact 
for the maintenance of the beds. The United States Fish Commission 
has recently planted oysters in Willapa Bay, Washington; Yaquina 
Bay, Oregon, and Humboldt Bay, California, but it is still too early to 
say with what success. 

The native oyster ( Ostrea lurida) of California, Oregon, and Washing- 
ton is found at various places on the coasts of the States mentioned, 
but attains its greatest size and perfection in Willapa Bay. It is much 
inferior to the eastern oyster in size, but its flavor is esteemed by many. 

In the Gulf of California is found a large species, Ostrea iridescens, 
which resembles the eastern species and is an object of some trade in 
the adjoining j)ortions of Mexico. Attempts have been made to intro- 
duce this form in the markets of San Francisco, but the mortality en 
route has been large and the venture unprofitable. 

Two smaller oysters, Ostrea palumea and Ostrea palumea glomerata, 
are also found in the Gulf of California. 

DESCRIPTION. 
EASTERN OYSTER, OSTREA VIRGINIANA. 

The shell of this species is generally elongate, but varies much with 
age and the conditions under which it grows. In the younger stages it 
is often nearly round, with ear-like projections on each side of the 
hinge and stout radiating ridges near the margin, thus bearing some 
resemblance to the European oyster. In shells which are actively 
growing there is a broad fringe of yellow cuticle around the edge of the 
valves, which, however, soon becomes thickened by a deposit of lime. 

The shell is subject to great variation in thickness, but it is rarely 
so thin as in the Pacific coast oyster. The exterior is marked by 
laminations and more or less concentric lines of growth; it is often 
covered by a yellowish cuticle, but is sometimes white and flinty in 
appearance. The inside of the shell is generally white, somewhat 
tinged with purple near the margins, and with a more or less pearly 
luster. The muscular impression is generally nearer to the posterior 



OYSTERS AND METHODS OF OYSTER-CULTURE. 267 

margin than to the hinge; it is a well-defined scar, kidney-shaped in 
specimens of ordinary size, but becoming more elongate in very large 
individuals; in young specimens it is pale, but it afterwards becomes 
purple or almost black. The left or lower valve is deeply concave 
within, the upper valve being flat or, usually, slightly concave. The 
animal portions are large, nearly filling the shell, and the mantle border 
is comparatively narrow. (Plate v.) 

PACIFIC COAST "NATIVE," OSTREA LURID A. 

The shell of this species is thin and irregular, varying in shape from 
almost round to elongate elliptical; the surface is sometimes laminated, 
but is never ribbed; the color is variable, being sometimes purple, 
sometimes dirty green or gray; the inside of the shell is greenish, 
sometimes tinged with purple. The muscular impression or scar is 
purple, but paler than in the eastern oyster, and its greatest length is 
usually longitudinal rather than transverse ; it is situated about mid- 
way between the hinge and the lips or nibs of the shell, and its ventral 
margin is usually prolonged toward the hinge. There is rarely a well- 
defined pit or excavation beneath the hinge, the inner face of the shell 
sloping off gently from the ligament. The lower valve is deeper than 
the upper one, but is rarely so strongly concave as in the eastern 
species. (Plate vi.) 

REPRODUCTION AND DEVELOPMENT. 
SEXUAL CHARACTERISTICS. 

In the European oyster the individuals are hermaphrodites — that is, 
each is both male and female; in the common eastern oyster the sexes 
are separate, each individual being either male or female, but not both. 

Although the sexes differ remarkably in physiology and minute 
anatomy, it is not possible to distinguish male from female by any 
known external characters. It is only by an examination of the genital 
glands, which in the male produce the spermatozoa or milt and in the 
female the ova, eggs, or spawn, or by examining the genital products 
themselves, that the one sex may be distinguished from the other. 

The differences between the ovaries of the female and the testes of 
the male are explained in the section treating of the anatomy. When 
the animals are ripe, the distinction of the sexes is most conveniently 
made by an examination of the genital products. A drop of genital 
fluid is extracted from the oyster in the manner described under the 
head of artificial fertilization (p. 332) and let fall into a glass of clear 
sea water. If the individual be a ripe female, the drop will break up 
into a uniformly distributed cloud, which, if examined against a black 
background, will be seen to consist of separate minute white granules 
or eggs. If the eggs be unripe, they will remain aggregated in little 
compound masses. If the specimen examined be a male, the drop of 
milt will form an irregular, stringy cloud, showing a tendency to drift in 



268 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 

streaks if the water be agitated, and with no particles distinguishable 
by the naked eye. 

Another test is to spread out a drop of the genital fluid, mixed with 
a drop of water, in a thin film upon a piece of glass, such as a micro- 
scope slide. If the specimen be a female, an examination with a strong 
hand lens will reveal many minute pear-shaped or oval bodies or eggs, 
each with a clear spot, the nucleus or so-called germinal vesicle. If the 
specimen be a male, the film can not be resolved into distinguishable 
particles when viewed with the lens, but consists of a milk-white mass,, 
having a quivering appearance owing to the effect of the combined 
movements of the indistinguishable spermatozoa. 

The histological characters which distinguish the testes and ovary 
are considered under the head of anatomy. 

According to Professor Sohiedt, an hermaphroditic oyster occurs on 
our northwest coast, the specimens examined coming from the State of 
Washington, the exact locality not being mentioned. Sexually, there- 
fore, this species resembles the common oyster of Europe. 

RIPENING OF THE GENERATIVE ORGANS. 

In spring, when the water begins to warm, certain changes begin to 
manifest themselves in the generative organs, preparatory to the act 
of spawning. In the female some of the minute eggs in the ovaries 
increase in size and become loosened in the follicles or little pockets of 
tissue in which they have undergone their early development. All of 
the eggs which are to be discharged in any one year do not ripen at the 
same time, so that the sj)awning of each individual extends over a 
greater or less period. An examination of the ovary at any time will 
always show great numbers of minute immature eggs, most of these 
being ova which will ripen and be discharged during some subsequent 
year. Other changes, which it is not necessary to mention here, take 
place in the eggs and tissues, but the ultimate result is that the ovary 
becomes enlarged by the growth of the ripening eggs and the latter 
pass into the oviducts, which stand out as milky- white and much- 
branched vessels on each side of the body. 

The spermatozoa develop in somewhat the same manner, but the 
generative cells, instead of developing into eggs, undergo rapid divi- 
sion, each into a number of minute active bodies, which pass into the 
sperm ducts and gorge them with a white fluid, the milt, in general 
naked-eye appearance closely resembling the ovarian fluid. 

SPAWNING. 

The act of spawning consists in the discharge of the ripe genital 
products into the surrounding water, where fertilization is left to chance. 

The genital ducts, one on each side, open into the chambers above 
the gills, and the ova in the one sex and the spermatozoa in the other, 
gradually oozing out of the openings, are caught up by the currents 
of water passing through the gill-canals and expelled from the body, 



OYSTERS AND METHODS OF OYSTER-CULTURE. 269 

together with the various waste products resulting from digestion and 
respiration. 

The season at which oysters spawn differs with the latitude of the 
bed and with local conditions. As a general rule, it may be said that 
they ripen earlier in the south than in the north, and that in the same 
region the genital products mature earlier in shallow than in deep water. 
These facts appear to be dependent primarily upon the temperature, 
other things being equal, southern waters warming before the northern, 
and the shallows before the depths. 

It is stated that the raccoon oyster of South Carolina spawns from 
the middle of March to the middle of August. Eipe individuals are 
found in shallow- water creeks during January and February, and it 
is probable that intermittent spawning may take place at any time 
during the year when favorable conditions prevail. In Chesapeake Bay 
oysters are found spawning from April to October, but apparently a 
few scattered individuals spawn at other times, though most of the spawn 
appears to be cast during the latter part of July or early in August. 
In Long Island Sound spawning takes place, according to the locality, 
during May, June, July, and August. Sometimes many oysters are 
found with well-developed ova during April, but this appears to be 
unusual, and Dr. Dean remarks that when it occurs "it will almost 
invariably be found that the spring has been warm and dry." 

Not only the time of spawning, but the quantity of spawn, appears 
to be affected by the weather conditions. Sudden changes produce 
very marked results, and a transfer of the oyster from one place to 
another during the spawning season is almost certain to interfere with 
reproduction or even absolutely arrest it. 

The age at which the oyster becomes capable of reproducing its kind 
varies with the locality, but it appears that in regions of rapid growth 
the generative organs ripen during the first year. The number of eggs 
discharged by the female is naturally dependent upon its size. Accord- 
ing to Dr. Brooks, the Maryland oyster of average size produces 
16,000,000 eggs each year, while a very large individual may produce 
60,000,000. The spermatozoa, being extremely minute, are present in 
the milt in inconceivable numbers. 

Notwithstanding the great fecundity of the individual oyster the 
reproductive power of the beds is not so vast as is generally supposed. 
If the oysters are scattered, or the number spawning at a given time is 
small, most of the genital matter will be wasted, as the contact of the 
male and female cells is entirely dependent upon chance, and the fewer 
such cells there are in a given body of water the smaller the probability 
of their meeting and fusing in the manner constituting the act of fer- 
tilization. Neither the eggs nor the spermatozoa live long after they 
are discharged from the parent, and if fertilization is to take place at 
all the two elements must be brought into'contact promptly ; and it will 
be seen, therefore, that nature must supply a vast number of germ cells 
to insure the survival of but a few. 



270 REPORT OF COMMISSIONEE OF FISR AND FISHEEIES. 



EMBRYONIC DEVELOPMENT. 

The following popular account of the early stages in the development 
of the oyster is slightly modified from the description by Dr. W. K. 
Brooks : 

The ovarian eggs are simply the cells of an organ of the body, the ovary, and they 
differ from the ordinary cells only in being much larger and more distinct from each 
other, and they have the power, when detached from the body, of growing and 
dividing up into cells, which shall shape themselves into a new organism like that 
from whose body the egg came. Most of the steps in this wonderful process may be 
watched under the microscope, and owing to the ease with which the eggs of the 
oyster may be obtained this is a very good egg to study. 

About 15 minutes after the eggs are fertilized they will be found to be covered with 
male cells, as shown in plate vn, fig. 1.* In about an hour the egg will be found to 
have changed its shape and appearance. It is now nearly spherical, as shown in plate 
xn, fig. 2, and the germiuative vesicle is no longer visible. The male cells may or may 
not still be visible upon the outer surface. In a short time a little transparent point 
makes its appearance on the surface of the egg and increases in size and soon forms 
a little projecting transparent knob — the polar globule — which is shown in plate vn, 
fig. 3, and in succeeding figures. 

Recent investigations tend to show that while these changes are taking place one of 
the male cells penetrates the protoplasm of the egg and unites with the germinative 
vesicle, which does not disappear but divides into two parts, one of which is pushed 
out of the egg and becomes the polar globule, while the other remains behind and 
becomes the nucleus of the developing egg, but changes its appearance so that it is 
no longer conspicuous. The egg now becomes pear-shaped, with the polar globule 
at the broad end of the pear, and this end soon divides into two parts, so that the 
egg (plate vn, fig. 4) is now made of one large mass and two slightly smaller ones, 
with the polar globule between them. 

The later history of the egg shows that at this early stage the egg is not perfectly 
homogeneous, but that the protoplasm which is to give rise to certain organs of the 
body has separated from that which is to give rise to others. 

The upper portion of the egg soon divides up into smaller and smaller spherules, 
until at the stage shown in plate vn, figs. 5, 6, and 7, we have a layer of small cells 
wrapped around the greater part of the surface of a single large spherule, and the 
series of figures shows that the latter is the spherule which is below in plate VII, fig. 4. 
This spherule now divides up into a layer of cells, and at the same time the egg, or 
rather the embryo, becomes flattened from above downward and assumes the shape 
of a flat oval disk. Plate vn, figs. 10 and 9, are views of the upper and lower surface of 
the embryo at about this time. In a sectional view, plate vn, fig. 11, it is seen to be 
made of two layers of cells, an upper layer of small transparent cells, e c, which are 
to form the outer wall of the body and which have been formed by the division of 
the spherules which occupj the upper end of the egg in plate vn, fig. 6, and a lower 
layer of much larger, more opaque cells, g, which are to become the walls of the 
stomach, and which have been formed by the division of the large spherule, a, of 
plate vn, fig. 6. 

This layer is seen in the section to be pushed in a little toward the upper layer, 
so that the lower surface of the disk-shaped embryo is not flat, but very slightly 
concave. This concavity is destined to grow deeper until its edges almost meet, and 
it is the rudimentary digestive cavity. A very short time after this stage has been 
reached, and usually within from two to four hours after the eggs were fertilized, 
the embryo undergoes a great change of shape and assumes the form which is shown 
in three different views in plate vn, figs. 12, 13, 14, and 15. 

* References to figures in quoted portions of this paper do not correspond with the 
originals, being altered to accord with their sequence in the present article. 



OYSTERS AND METHODS OF OYSTER-CULTURE. 271 

A circular tuft of long hairs or cilia has now made its appearance at what is thus 
marked as the anterior end of the body, and as soon as these hairs are formed they 
begin to swing backward and forward iu such a way as to constitute a swimming 
organ, which rows the little animal up from the bottom to the surface of the water, 
where it swims around very actively by the aid of its cilia. This stage of develop- 
ment, plate vn, fig. 12, which is of short duration, is of great importance in raising the 
young oysters, for it is the time when they can best be siphoned off into a separate 
vessel and freed from the danger of being killed by the decay of any eggs which 
may fail to develop. On one surface of the body at this stage, the dorsal surface, 
there is a well-marked groove, and when a specimen is found in a proper position for 
examination the opening into the digestive tract is found at the bottom of this groove. 
Plate vn, fig. 13, is a sectional view of such an embryo. It is seen to consist of a cen- 
tral cavity, the digestive cavity, which opens externally on the dorsal surface of the 
body by a small orifice, the primitive mouth, and which is surrounded at all points, 
except at the mouth, by a wall which is distinct from the outer wall of the body. 
Around the primitive mouth these two layers are continuous with each other. 

The way in which this cavity, with its wall and external opening, has been formed 
will be understood by a comparison of plate vn, fig. 13, with plate vn, fig. 8. The 
layer which is below in plate vn, fig. 8, has been pushed upward in such a way as to 
convert it into a long tube, and at the same time the outer layer has grown downward 
and inward around it, and has thus constricted the opening. The layer of cells which 
is below in plate vn, fig. 8, thus becomes converted into the walls of the digestive 
tract, and the space which is outside and below the embryo, in plate vn, fig. 8, becomes 
converted into an inclosed digestive cavity, which opens externally by the primitive 
mouth. 

This stage of development, in which the embryo consists of two layers, an inner 
layer surrounding a cavity which opens externally by a mouth-like opening, and an 
outer layer which is continuous with the inner around the margins of the opening, 
is of very frequent occurrence, and it has been found, with modifications, in the most 
widely separated groups of animals, such as the starfish, the oyster, and the frog; 
and some representatives of all the larger groups of animals, except the protozoa, 
appear to pass during their development through a form which may be regarded as 
a more or less considerable modification of that presented by our embryo oyster. 
This stage of development is known as the gasirula stage. 

The edges of the primitive mouth of the oyster continue to approach each other 
and finally meet and unite, thus closing up the opening, as shown in plate vn, fig. 16 
and leaving the digestive tract without any communication with the outside of the 
body, and entirely surrounded by the outer layer. The embryo shown in plate vn, 
figs. 12 and 16, are represented with the dorsal surface below, in order to facilitate 
comparison with the adult, but in plate VII, fig. 17, and most of the following figures, 
the dorsal surface is uppermost, for more ready comparison with the adult. 

In other lamellibranchs, and doubtless also in the oyster, the shell 
begins as a deposit in an invagination or pocket on the dorsal side of 
the body. In its manner of formation this shell-gland resembles the 
primitive mouth for which it has been more than once mistaken by 
iuvesti gators. In some forms the shell is at first single, but in the 
oyster they are said to be separated from each other from the beginning, 
and appear independently. Dr. Brooks says further : 

Soon after they make their appearance, the embryos cease to crowd to the surface 
of the water and sink to various depths, although they continue to swim actively in 
all directions, and may still be found occasionally close to the surface. The region 
of the body which carries the cilia now becomes sharply defined, as a circular pro- 
jecting pad, the velum, and this is present and is the organ of locomotion at a much 
later stage of development. It is shown at the right side of the figure in plate vn, 



272 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 

fig. 17, and in plate vn, fig. 18, it is seen in surface view, drawn in between the shells, 
and with its cilia folded down and at rest, as they are seen when the little oyster 
lies upon the bottom. 

The two shells grow rapidly, and soon become quite regular in outline, as shown in 
plate vn, fig. 17, and plate viii, fig. 1, but for some time they are much smaller than the 
body, which projects from between their edges around their whole circumference, 
except that along a short area, the area of the hinge upon the dorsal surface, where 
the two valves are in contact. 

The two shells continue to grow at their edges, and soon become large enough to 
cover up and project a little beyond the surface of the body, as shown in plate viii, 
fig. 1, and at the same time muscular fibers make their appearance and are so arranged 
that they can draw the edge of the body and the velum in between the edges of the 
shells in the manner shown in plate vn, fig. 18. In this way that surface of the body 
which lines the shell becomes converted into the two lobes of the mantle, and 
between them a mantle cavity is formed, into which the velum can be drawn when 
the animal is at rest. While these changes have been going on over the outer sur- 
face of the body other important internal modifications have taken place. We left 
the digestive tract at the stage shown in plate vn, fig. 16, without any communica- 
tion with the exterior. 

Soon the outer wall of the body becomes pushed inward to form the true mouth, 
at a point (plate vn, fig. 17) which is upon the ventral sur-face and almost directly 
opposite the point where the primitive mouth was situated at an earlier stage. The 
digestive cavity now becomes greatly enlarged and cilia make their appearance 
upon its walls, the mouth becomes connected with the chamber which is thus formed 
and which becomes the stomach, and minute particles of food are drawn in by the 
cilia and can now be seen inside the stomach, where the vibration of the cilia keep 
them in constant motion. Up to this time the animal has developed without growing, 
and at the stage shown in plate vn, fig. 16, it is scarcely larger than the unfertilized 
egg, but it now begins to increase in size. The stages shown in plate viii, fig. 1, and 
plate vn, fig. 18, agree pretty closely with the figures which the European embry- 
ologists give of the oyster embryo at the time when it escapes from the mantle 
chamber of its parent. The American oyster reaches this stage in from twenty-four 
hours to six days after the egg is fertilized, the rate of development being deter- 
mined mainly by the temperature of the water. 

Soon after the mantle has become connected with the stomach this becomes united 
to the body wall at another point a little behind the mantle, and a second opening, 
the anus, is formed. The tract, which connects the anus with the stomach, lengthens 
and forms the intestine, and soon after the sides of the stomach become folded off 
to form the two halves of the liver, as shown in plate viii, fig. 1. Various muscular 
fibers now make their appearance within the body, and the animal assumes the form 
shown in plate viii, fig. 1, and plate vn, fig. 18.* 

What follows this stage may be best told in the words of Professor 
Huxley, who speaks of the European oyster, in which the metamor- 
phosis from the free-swimming fry to the fixed spat and finally the 
adult oyster is essentially the same as in our species. 

The young animal which is hatched out of the egg of the oyster is extremely 
unlike the adult, and it will be worth while to consider its character more closely 
than we have hitherto done. 

Under a tolerably high magnifying power the body is observed to be inclosed in a 
transparent but rather thick shell (plate viii, fig. 2, L), composed, as in the parent, 
of two valves united by a straight hinge, h. But these valves are symmetrical and 
similar in size and shape, so that the shell resembles that of a cockle more than it 
does that of an adult oyster. In the adult the shell is composed of two substances 

*Report Maryland Fish Commission, Annapolis, 1880, pp. 19-25, in part. 






OYSTERS AND METHODS OP OYSTER-CULTURE. 273 

of different character, the outer brownish, with a friable prismatic structure, the 
inner dense and nacreous. In the larva there is no such distinction, and the whole 
shell consists of a glassy substance devoid of any definite structure. 

The hinge line answers, as in tbe adult, to the dorsal side of the body. On the 
opposite or ventral side the wide mouth m and the minute vent v are seen at no 
great distance from one another. Projecting from the front part of tbe aperture of 
the shell there is a sort of outgrowth of the integument of what we may call the back 
of the neck into a large oval thick -rimmed disk termed the velum, vl, the middle of 
which presents a more or less marked prominence. The rim of tbe disk is lined with 
long vibratile cilia, and it is the lashing of these cilia whicb propels the animal, and, 
in the absence of gills, probably subserves respiration. The funnel-shaped mouth 
has no palps; it leads into a wide gullet, and this into a capacious stomach. A 
sac-like process of tbe stomach on either side (the left one, 1, only is shown in fig. 2) 
represents the "liver." The narrow intestine is already partially coiled on itself, and 
this is the only departure from perfect bilateral symmetry in the whole body of the 
animal. The alimentary canal is lined throughout with ciliated cells, and the vibra- 
tion of these cilia is the means by Avhich the minute bodies which serve the larva for 
food are drawn into the digestive cavity. 

There are two pairs of delicate longitudinal muscles, rs ri, which are competent to 
draw back the ciliated velum into the cavity of the shell, when the animal at once 
sinks. The complete closure of the valves is effected, as in the adult, by an adductor 
muscle, am, the fibers of which pass from one valve to the other. But it is a very 
curious circumstance that this adductor muscle is not the same as that which exists 
in the adult. It lies, in fact, in the forepart of the body and on the dorsal side of 
the alimentary canal. The great muscle of the adult, fig. 3, M, on the other hand, 
lies on the ventral side of the alimentary canal and in the hinder part of the body. 
And as tbe muscles, respectively, lie on opposite sides of the alimentary canal, that 
of the adult can not be that of the larva, which has merely shifted its position; for 
in order to get from one side of the alimentary canal to the other it must needs cut 
through that organ; but as in the adult no adductor muscle is discoverable in the 
position occupied by that of the larva or anywhere on the dorsal side of the aliment- 
ary canal, while on tbe other hand there is no trace of any adductor on the ventral 
side in the larva, it follows that the dorsal or anterior adductor of the larva must 
vanish in the course of development, and that a new ventral or posterior adductor 
must be developed to play the same part and replace the original muscle functionally, 
though not morphologically. 

* X # * # *• * 

When tbe free larva of the oyster settles down into the fixed state, the left lobe of 
the mantle stretches beyond its valve, and, applying itself to the surface of the stone 
or shell to which the valve is to adhere, secretes shelly matter, which serves to cement 
the valve to its support. As the animal grows the mantle deposits new layers of 
shell over its whole surface, so that the larval shell valves become separated from 
the mantle by the new layers (plate vm, fig. 3, S), which crop out beyond their 
margins and acquire the characteristic prismatic and nacreous structure. The sum 
raits of the outer faces of the umbones thus correspond with the places of the larval 
valves, whicb soon cease to be discernible. After a time the body becomes convex 
on the left side and fiat on the right ; the successively added new layers of shell mold 
themselves upon it, and the animal acquires the asymmetry characteristic of the 
adult." 

The horny convex shell of the fry (plate vm, fig. 3, L) may be seen, for 
a considerable time after attachment, at the umbo or beak of the develop- 
ing shell of the spat (plate vm, fig. 3, 8). The under or attached valve of 
the latter at first conforms closely to the surface to which it has become 

* Huxley, Thomas H. Oysters and the Oyster Question. The English Illustrated 
Magazine, London, Oct. 1883 and Nov. 1883, vol. 1, pp. 47-55, and pp. 112-121, 

F. C. K. 1897 18 



274 REPORT OF COMMISSIONER OF FISH AND FISHERIES 

attached, being usually flat, but afterwards, as a rule, becoming deep 
and strongly concave, through an upgrowing along the edges. 

FIXATION, SET, OR SPATTING. 

At the time of fixation the fry will, under proper conditions, attach 
itself by its left valve to any hard or firm body with which it may come 
in contact. 

The first essential is that the surface should be clean and that it 
should remain so a sufficient length of time to enable the young oyster 
to firmly establish itself. So long as this condition obtains, the nature 
of the material seems to matter but little. In most bodies of water the 
spat fixes itself at all levels from the surface to the bottom, but in cer- 
tain parts of the coast its place of attachment is confined to the zone 
between high and low water, the mid-tide mark being the place of max- 
imum fixation. It has been suggested that this was due to the density 
of the water preventing the sinking of the fry. There are a number 
of objections to this theory, but no better one has been offered, and it 
may receive provisional acceptance. 

GROWTH. 

At the time of its attachment the oyster fry measures about one- 
eightieth or one-ninetieth of an inch in diameter. The valves of the 
shell are strongly convex and symmetrical, and are composed of a 
horny material quite different from the finished shell of the adult. 

The mantle, a thin flap of tissue which envelops the body of the 
oyster on each side, projects freely from between the lips of the valves 
and is the organ which secretes the shell. Upon its outer surface suc- 
cessive layers of horny material are laid down, these becoming impreg- 
nated with calcareous matter arranged in a prismatic manner, and thus 
forming the stony shell which characterizes the adult. 

The mantle increases pari passu with the growth of the soft parts in 
general, and as it is always capable of protrusion a little beyond the lips 
of the valves, it follows that each successive layer of shell is slightly 
larger than that which preceded it, and the shell increases in length 
and breadth as well as in thickness. From the nature of its growth, 
therefore, the youngest or newest part of the shell is on the inner face 
and at the edges, the latter always being sharp and thin in a growing 
oyster. The shell of the young oyster is always thin and delicate, and 
is generally more rounded than in the adult. The lower valve at first 
adheres closely to the body to which it is attached, but later its edge 
grows free and the valve, as a whole, becomes deeper and more capa- 
cious than its fellow. The small larval or fry shell remains visible at 
the beak of the spat shell for a considerable time, but becomes eroded 
away before the oyster reaches the adult condition. 

The soft parts of the oyster assume their adult form in general soon 
after attachment, although the genital glands do not become functional 
until a much later j>eriod. 



OYSTERS AND METHODS OF OYSTER-CULTURE. 275 

The rate of growth (plates x, xi, xn, xm) varies with locality and 
conditions. It is more rapid when food is abundant and at seasons 
when the oyster is feeding most vigorously, these conditions being filled 
most thoroughly in summer and fall, when the warm water increases 
the vital activities of both oyster and food. 

In South Carolina oysters not more than six or seven months old were 
found to have reached a length of 2£ inches, and in the warm sounds 
of North Carolina they reach a length of 1^ inches in from two to three 
months. In the coves and creeks of Chesapeake Bay they attain about 
the same size by the end of the first season's active growth, and by the 
time they are two years old they measure from 2^ to 3| inches long and 
from 2 to 3 inches wide. On the south side of Long Island the growth 
of the planted oysters is much more rapid than in Connecticut, it being 
stated that "two-year plants" set out in spring are ready for use in the 
following fall, while upon the Connecticut shore it would require two or 
three years to make the same growth. On the south side of Long Island 
oysters If inches long in May have increased to 3 inches by November 
of the same year. 

The amount of lime in the water is a factor in determining the 
character of the shell, and oysters growing in waters deficient in that 
respect have thinner shells than those which are well supplied, and are 
therefore more susceptible to the attacks of the drill. 

The shape of the oyster to a certain extent determines its value in 
the market. Single oysters of regular shape with deep shells and 
plump bodies will bring a better price than those which are irregular 
and clustered. The shape depends largely upon the degree of crowding 
to which the oyster has been subject. When numerous spat become 
attached to a single piece of cultch, such as an oyster shell, there is 
often insufficient room for the development of all. Many will be crowded 
out and suffocated, while the survivors will be distorted through the 
necessity of conforming to the irregular spaces between the valves of 
their fellows. Sometimes the pressure exerted between the rapidly 
growing shells is sufficient to break up the more fragile forms of cultch, 
and the separated oysters then usually improve somewhat in shape. 

The crowding of oysters reaches its climax upon the "raccoon" 
oyster beds. Raccoon oysters are usually found in localities where the 
bottom is soft and the only firm place which offers itself for the attach- 
ment of the spat is upon the shells of its ancestors. Temperature and 
other conditions are favorable, growth is rapid, the young oysters are 
crowded into the most irregular shapes, the shells are long, thin, and 
sharp-edged, and eventually the mass of young is so dense that it 
crowds out and smothers the preceding generations which produced it 
and offered means for its attachment. Oysters crowded in this excessive 
manner are poor-flavored as well as ill-shaped, but both defects are 
corrected if they be broken apart, as may be readily done, and planted 
elsewhere. 



276 REPORT OF COMMISSIONER OP FISH AND FISHERIES. 



ANATOMY. 

The following popular description of the anatomy of the oyster is 
extracted from the writings of Professors Brooks and Ryder: 

The general structure of an oyster niay be roughly represented by a long, narrow 
memorandum book, with the back at one of the narrow ends instead of one of the 
long ones. The covers of such a book represent the two shells of the oyster, and the 
back represents the hinge, or the area where the two valves of the shell are fastened 
together by the hinge ligament. (Plate i, fig. 11.) This ligament is an elastic, dark- 
brown structure, which is placed in such a relation to the valves of the shell that it 
tends to throw their free ends a little apart. In order to understand its manner of 
working, open the memorandum book and place between its leaves, close to the back, 
a small piece of rubber to represent the ligament. If the free ends of the cover are 
pulled together the rubber will be compressed and will throw the covers apart as 
soon as they are loosened. The ligament of the oyster shell tends, by its elasticity, 
to keep the shell open at all times, and while the oyster is lying undisturbed upon 
the bottom, or when its muscle is cut, or when the animal is dying or dead, the 
edges of the shell are separated a little. 

The shell is lined by a thin membrane, the mantle (plate i, fig. 1, mt), which folds 
down on each side, and may be compared to the leaf next the cover on each side of 
the book. The next two leaves of each side roughly represent the four gills, g, the 
so-called "beard" of the oyster, which hang down like leaves into the space inside 
the two lobes of the mantle. The remaining leaves may be compared to the body or 
visceral mass of the oyster. 

Although the oyster lies upon the bottom, with one shell above and one below, the 
shells are not upon the top and bottom of the body, but upon the right and left 
sides. The two shells are symmetrical in the young oyster (plate viii, fig. 2), but after 
it becomes attached the lower or attached side grows faster than the other and 
becomes deep and spoon-shaped, while the free valve remains nearly flat. In nearly 
every case the lower or deep valve is the left. As the hinge marks the anterior 
end of the body, an oyster which is held on edge, with the hinge away from the 
observer and the flat valve on the right side^ will be placed with its dorsal surface 
uppermost, its ventral surface below, its anterior end away from the observer, and 
its posterior end toward him, and its right and left sides on his right and left hands, 
respectively. 

In order to examine the soft parts, the oyster should be opened by gently working 
a thin, flat knife blade under the posterior end of the right valve of the shell, and 
pushing the blade forward until it strikes and cuts the strong adductor muscle, M, 
which passes from one shell to another and pulls them together. As soon as this 
muscle is cut the valves separate a little, and the right valve may be raised up and 
broken off from the left, thus exposing the right side of the body. The surface of 
the body is covered by the mantle, a thin membrane which is attached to the body 
over a great part of its surface, but hangs free like a curtain around nearly the whole 
circumference. By raising its edge, or gently tearing the whole right half away 
from the body, the gills, g, will be exposed. These are four parallel plates which 
occupy the ventral half of the mantle cavity and extend from the posterior nearly 
to the anterior end of the body. Their ventral edges are free, but their dorsal edges 
are united to each other, to the mantle, and to the body. The space above, or dorsal 
to the posterior ends of the gills, is occupied by the oval, firm adductor muscle, M, 
the so-called "heart." For some time I was at a loss to know how the muscle 
came to be called the "heart," but a friend told me that he had always supposed 
that this was the heart, since the oyster dies when it is injured. The supposed 
" death " is simply the opening of the shell, when the animal loses the power to 
keep ifc shut. Between this muscle and the hinge the space above the gills is occupied 



.Report U. S. F. C. 1897. (To face page 276.) 



Plate 




Fig. 1. Oyster with right shell and mantle removed, a and o, origin of arteries from the ventricle- 
au, auricle ot heart; br, vessel carrying blood from the gills to the auricle of the heart; bj outline 
of organ ot bojanus. the so-called kidney; bp, pores from which the water issues into the branchial 
canals after passing through the sills; cl, cloaca; d, pg. and sg, connective and two ganglia of the 
nervous system; g, gills; gc, cavity between the two mantle folds; h, hinge; I, ligament- M ad- 
ductor muscle; m, mouth; mt, mantle, the arrows show the direction of currents produced by the 
cilia; p, palps; p', outer end of right pedal muscle; s, external opening of sexual and renal organs 
of right side; V, anus; ve. ventricle of heart. 

Pig. 2. Diagram to show sexual organs of the oyster, d, duct of sexual gland. Other letters as above. 



OYSTERS AND METHODS OF OYSTER-CULTURE. 277 

by the body, or visceral mass, which is made up mainly of the light-colored repro- 
ductive organs and the dark-colored digestive organs, packed together in one 
continuous mass. 

If the oyster has been opened very carefully, a transparent, crescent-shaped space 
will be seen between the muscle and the visceral mass. This space is the pericar- 
dium, and if the delicate membrane which forms its sides be carefully cut away, the 
heart, ve and au, may be found without any difficulty lying in this cavity and pulsat- 
ing slowly. If the oyster has been opened roughly, or if it has been out of water for 
some time, the rate of beating may be as low as one a minute, or even less, so the heart 
must be watched attentively for some time in order to see one of the contractions. 

In front of the gills, that is, between them and the hinge, there are four fleshy 
flaps — the lips, p, two on each side of the body. They are much like the gills m 
appearance, and they are connected with each other by two ridges, which run across 
the middle of the body close to the anterior end, and between these folds is the large 
oval mouth, m, which is thus seen to be situated, not at the open end of the shell, 
but as far away from it as possible. As the oyster is immovably fixed upon the 
bottom, and has no arms or other structures for seizing food and carrying it to the 
mouth, the question how it obtains its food at once suggests itself. If a fragment of 
one of the gills is examined with a microscope it will be found to be covered with very 
small hairs, or cilia, arranged in rows, plate viii, fig. 3, c. Each of these cilia is 
constantly swinging back and forth with a motion something like that of an oar in 
rowing. The motion is quick and strong in one direction and slower in the other. 
As all the cilia of a row swing together they act like a line of oars, only they are 
fastened to the gill, and as this is immovable they do not move forward through the 
water, but produce a current of water in the opposite direction. This action is not 
directed by the animal, for it can be observed for hours in a fragment cut out of 
the gill, and if such a fragment be supplied with fresh sea water the motion will 
continue until it begins to decay. While the oyster lies undisturbed on the bottom, 
with its muscle relaxed and its shell open, the sea water is drawn on to the gills by 
the action of the cilia, for although each cilium is too small to be seen without a 
microscope, they cover the gills in such great numbers that their united action pro- 
duces quite a vigorous stream of water, which is drawn through the shell and is then 
forced through very small openings on the surfaces of the gills into the water tubes 
inside the gills, and through these tubes into the cavity above them, and so out of 
the shell again. As the stream of water passes through the gills the blood is aerated 
by contact with it. 

The food of the oyster consists entirely of minute animal and vegetable organisms 
and small particles of organized matter. Ordinary sea water contains an abundance 
of this sort of food, which is drawn into the gills with the water, but as the water 
strains through the pores into the water tubes the food particles are caught on the 
surface of the gills by a layer of adhesive slime, which covers all the soft parts of 
the body. As soon as they are entangled the cilia strike against them in such a way 
as to roll or slide them along the gills toward the mouth. When they reach the 
anterior ends of the gills they are pushed off and fall between the lips, and these 
again are covered with cilia, which carry the particles forward until they slide 
into the mouth, which is always wide open and ciliated, so as to draw the food 
through the cesophagus into the stomach. Whenever the shell is open these cilia 
are in action, and as long as the oyster is breathing a current of food is sliding into 
its mouth. 

The cilia and particles of food are too small to be seen without a microscope, but 
if finely powdered carmine be sprinkled over the gills of a fresh oyster, which has 
been carefully opened and placed in a shallow dish of sea water, careful observation 
will show that as soon as the colored particles touch the gills they begin to slide 
along with a motion which is quite uniform, but not much faster than that of the 
minute-hand of a watch. This slow, steady, gliding motion, without any visible 



278 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 

cause, is a very striking sight, and. with a little care the particles may be followed 
up to and into the mouth. 

In order to trace the course of the digestive organs, the visceral mass may be split 
with a sharp knife or razor. If the split is pretty near the middle of the body each 
half will show sections of the short, folded oesophagus, running upward from the 
mouth, and the irregular stomach, cut 1, s, with thick, semi-transparent walls, sur- 
rounded by the compact, dark-greenish liver, 1 1. Back of the liver and stomach the 
convoluted intestine, i, will be seen, cut irregularly at several points by the section. 

There are no accessory organs of reproduction, and the position, form, and general 
appearance of the reproductive organ, plate i, fig. 2, is the same in both sexes. As the 
reproductive organ has an opening on each side of the body, it is usually spoken of 
as double, but in the adult oyster it forms one continuous mass, with no trace of a 
division into halves, and extends entirely across the body and (against) the bends 
and folds of the digestive tract. * 




Cut 1. 



The stomach is pretty definitely marked off from the other portions of the digest- 
ive tract. It may be said to be that portion of the latter which is surrounded by the 
liver. The portion of the intestine immediately following the short, widened region 
which we regarded as the stomach is the most spacious portion of the gut, and in it 
is lodged a very singular organ, which has been called the "crystalline style." This 
is an opalescent rod of a glass-like transparency and gelatinous consistence, which 
measures according to the size of the oyster from half an inch up to one and a half 
inches in length. Its anterior end is the largest, and in a large specimen measures 
nearly an eighth of an inch in diameter, but at its posterior end is scarcely half as 
thick; both ends are bluntly rounded. I fell into an error in supposing that this 
style was lodged in a special pouch or sac, as described in my report to the Maryland 
commissioner in 1880. The "crystalline style" really lies in the first portion of the 
intestine and extends from the pyloric end of the stomach to the first bend of the 



* Brooks, W. K. Studies from the Biological Laboratory of Johns Hopkins Univer- 
sity, No. iv, 1888, pp. 5-10 in part. 



OYSTERS AND METHODS OF OYSTER-CULTURE. 279 

intestine, where there is a marked constriction of the alimentary canal. It appears, 
therefore, to he a sort of loose valve in the cavity of the gut ; its function may be to 
prevent coarse particles of food from passing or it may in some way assist digestion. 
In specimens hardened in acid or alcohol this rod is destroyed, or at least disappears, 
so that I have been unable to find it. The greater portion of its substance is appar- 
ently made up of water. 

The peculiar double induplication of the wall of the intestine is described in 
another place. The fecal matters are extruded in the form of a demi-cylinder, with 
one side excavated in a groove-like manner. This shape of the fecal matters is due 
to the presence of the double fold. The feces themselves are composed of extremely 
fine particles of quartz or sand grains, the tests of diatoms, organic matters, humus, 
cellulose, fragments of the chitinous coverings of some of the minute worms and 
articulates, etc., which have been swallowed and digested by the animal. The anus, v, 
is situated on the dorsal side of the great adductor muscle where the intestine ends. 

The organs of sensation of the oyster, though not very higbly developed, are of 
sufficient importance to merit attention. The auditory sense, although I have never 
been able to dissect out the auditory vesicles, I am satisfied exists, because one can 
not noisily approach an oyster bank where the oysters are feeding without their 
hearing so that instantly every shell is closed. The tentacles of the mantle are often 
extended until their tips reach beyond the edges of the valves. If the animal in 
this condition is exposed to a strong light the shadow of the hand passing over it is 
a sufficient stimulus to cause it to retract the mantle and tentacles and to close its 
parted valves. The mantle incloses, like a curtain, the internal organs of the crea- 
ture on either side, and lies next the shell, and, as already stated, secretes and 
deposits the layers of calcic carbonate composing the latter. The free edges of the 
mantle, which are purplish, are garnished with small, highly sensitive tentacles of 
the same color. These tentacles are ciliated and serve as organs of touch, and also 
appear to be to some extent sensitive to light. 

The nervous system of the oyster is very simple, and, as elsewhere stated, is to 
some extent degenerate in character. It is composed of a pair of ganglia or knots of 
nervous matter, plate i, fig. 1, sg, which lie just over the gullet, and from these a pair 
of nervous cords, d, pass backward, one on each side, to join the hinder pair which lie 
just beneath the adductor muscle, p g. The mantle receives nerve branches from the 
hindmost ganglia or knots of nervous matter; these, as their centers, control the 
contraction and elongation of the radiating bundle of muscular fibers, as well as 
those which lie lengthwise along the margin ; the former contract and withdraw the 
edges of the mantle from the margin of the shell, while the latter in contracting 
tend to crimp or fold its edges. The tentacles are mainly innervated by fibers 
emanating from the hindmost ganglia, while the internal organs are innervated from 
the head or cephalic ganglia. The hind ganglia also preside over the contractions 
of the great adductor muscle. The nerve threads which radiate outward from it to 
the tentacles dispatch the warnings when intruders are at hand that it must contract 
and close the shells.* 

* Ryder, John A. ; Fishery Industries of the United States, pp. 714-715. 



280 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 

PHYSICAL, AND BIOLOGICAL CONDITIONS ON OYSTER-BEDS. 
TEMPERATURE OF WATER. 

The oyster lives in waters of widely varying temperature, both as to 
the average for the year and the extremes met with at different 
seasons. Perhaps the greatest divergence between the extremes is 
in Chesapeake Bay, where the range is from the freezing-point of 
brackish water, something below 32°, to 90° F. In New Jersey and in 
Chesapeake Bay the shallow-water oysters, which are exposed or 
nearly exposed at low water, are frequently frozen, an event which is 
not necessarily fatal if they are gradually thawed. Young oysters 
in shallow water are sometimes " winter-killed," or their vitality is 
seriously reduced, by exposure to exceptionally low temperatures. The 
remedy, or rather preventive, is to remove to deeper water in the fall, 
and seed oysters on natural spatting-grounds may often be saved by 
this means. 

In deeper water, such as is found on the offshore beds of Long Island 
Sound, they are not subject to such severe trials, but are nevertheless 
called upon to withstand, during several months, a temperature not far 
from 32° F. In the Long Island oyster region the summer temperature 
of the water reaches 75° F., and from May 1 to November 1 probably 
never falls below 60° F. On the South Carolina oyster-beds the tem- 
perature appears to rarely fall below 55° F., but, on the other hand, 
the exposed banks of that region are subjected to the direct rays of the 
sun and therefore withstand a temperature considerably higher than 
that to which submerged oysters are liable. 

The temperature has an important bearing upon the food supply. 
When the water is warm there is a rapid multiplication of the small 
forms upon which the oyster feeds, and at the same time the activities 
of the oyster itself are quickened. The two facts taken together result 
in a more rapid growth of the oyster than is likely to take place in 
colder waters. 

It is often said that "plants do not spawn," and there appears to be 
some truth in the statement if we apply it to a period of a year or so 
after planting, and refer to cases in which the transplanting has induced 
considerable modification in the conditions under which the oyster is 
placed. This fact is no doubt largely due to the changes in temperature 
to which the oyster is subjected when transplanted. Dr. Ryder says : 

A very short exposure of the animal to water of an increased temperature caused 
a deterioration of the generative matter. I have tried to fertilize the eggs of num- 
bers of oysters that had lain over night in the Quinnipiak River aud invariably 
failed; the eggs in every case appeared to be overripe. Oysters taken from the bed 
at the same time and from the same locality, but kept in a basket over night, gave 
good results. 

The same investigator found that at Beaufort, N". C, the best results 
in fertilization were obtained the nearer the temperature was to 70° F. 
Both at Beaufort and in Chesapeake Bay the embryos develop most 



OYSTERS AND METHODS OF OYSTER-CULTURE. 281 

rapidly in waters between 74° and 80° F., although the mortality is 
greater than at a slightly lower temperature. Under such conditions 
the embryos reach the swimming stage in from 3 to 10 hours, a fact 
which is, of course, advantageous to those undertaking artificial propa- 
gation. When the temperature falls to below 65° F., development 
almost ceases, and when it rises above 80° F. but few of the embryos 
reach the swimming stage. Sudden changes are usually fatal, and cold 
rains kill great numbers of the swimming fry. 

Dr. Eyder recommends "that the prevalent temperature of the water 
during the spawning season shall range from 68 to 80° F." It is quite 
possible that in other regions, with oysters native thereto, or even those 
which have been acclimated therein, some other temperature may be 
found more favorable, but no data bearing upon the matter have been 
published. 

TEMPERATURE; PLANTED BEDS IN SAN FRANCISCO BAY. 

The temperature at San Francisco is usually not much higher in 
summer than in winter, but information upon the subject is limited. 
Upon the oyster-beds at Millbrae it is said to vary from 58° to 65° F., 
but at the extreme southern end of the bay it ranges from 67° to 74° F. 
In October, 1890, Mr. O. H. Townsend found 61° F. at Belmont; at San 
Mateo, nearer the sea, 60° F., and at California city, 57° F. 

In midsummer the temperature was considerably higher; between 
July 12, 1891, and September 7, 1891, it ranged from 67° to 74° F., the 
means for 10-day periods during the same time being between 69.1° 
and 72° F. As Mr. Townsend points out, there is, therefore, a con- 
siderable period during the summer when the temperature, in portions 
of the bay at least, is favorable for spawning of the planted eastern 
oysters. The portions of the bay near the sea appear to have a tem- 
perature several degrees cooler than in the southern portions. 

DENSITY OF WATER. 

Oysters are found living in water ranging in salinity from 1.002* to 
1.025, but the lower densities are always injurious, and prolonged 
exposure to their influence is fatal to oyster life. It is not possible to 
profitably maintain oyster-beds in waters where the density falls below 
1.007 for any length of time, the oyster, if not killed, becoming poor in 
quality, pale, watery, and tasteless. Heavy freshets, such as occur in 
the rivers discharging into Chesapeake Bay and at various places on 
the Gulf coast, frequently so lower the density of the water as to prac- 
tically exterminate the oysters on certain beds. Experience apparently 
indicates that the best oysters are grown in densities between about 
1.011 and 1.022, the former being approximately the specific gravity 
over the Tangier Sound beds, the latter that over the deep-water 
oyster-grounds of Long Island Sound. 

*Tke figures represent the specific gravity as measured with the salinometer, that 
of pure water heing 1.000. 



282 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 

Change of density has an important effect upon the spawning of 
oysters. At St. Jerome Creek, Dr. Ryder found that the eggs could 
not be impregnated in a density much exceeding that in which the 
parent animals live. With oysters raised in water ranging from 1.007 
to 1.0095 it was found that the milt was killed by a density greater 
than 1.013, the individual spermatozoa losing their mobility in a few 
moments when exposed to the greater density. The frequent failure 
of oysters to spawn in the season in which they are transplanted is 
perhaps in a measure owing to this cause. In Chesapeake Bay they 
are usually transplanted from deeper, denser water to more shallow 
and less dense, and when taken from the Chesapeake to Long Island 
Sound they go through a similar experience. There is at the same 
time, however, usually a change in temperature, and doubtless both 
factors combine to produce the effect noticed. 

It has been suggested by Lieutenant Piatt that the density of the 
water has an effect on the distribution of the set; that is, the specific 
gravity of the swimming embryo is such that it can not sink in 
dense water and therefore must become attached in marginal beds 
between tide marks, as is seen on the "raccoon" oyster-beds of South 
Carolina. 

In some places it has been found that the best results in oyster- 
culture are to be had in brackish water, and Dr. ttyder suggests that 
this may be largely due to the fact that water of the lower densities 
is usually shallower, and consequently warmer and better adapted to 
the production of an abundant supply of the minute organisms which 
constitute the principal source of the oyster's food. There can be no 
doubt, however, that the eastern oyster is distinctively a brackish- 
water form. It has been found that it will not thrive in French waters 
perfectly adapted to the culture of the European species, and there is 
reason to believe that it will reproduce itself in a lower density than is 
necessary for the native oyster of California. 

For determining the temperature and the density of sea waters the 
apparatus shown in plate n is used. It consists of a glass float with a 
long stem and a large bulb, weighted so as to sink in fresh water to^T 
point near the top of the stem. The stem is graduated to read between 
1.000 and 1.031, the figures representing the specific gravity; that is, 
they show the weight of the salt water, an equal body of fresh water 
being supposed to weigh 1.000. 

In practice a scale having the entire range would be too long for 
safety and convenience, and therefore the salinometers are made in 
sets of three, reading from 1.000 to 1.011, from 1.010 to 1.021, and from 
1.020 to 1.031, respectively. 

There is also provided with them a deep copper cup or cylinder, 
at one side of which a thermometer is attached (plate n). The method 
of using the salinometer is as follows : The cup is filled with the water 
to be tested, the appropriate float is placed in the water, the density of 



Report U. S. F. C. 1897. (To face page 282.) 



Plate II 




SCALE 



SALINOMETER AND SALINOMETER CUP. 

The tcale opposite the stem of the salinometer represents that of the high reading spindle as if unrolled. 
It registers densities between 1.020 and 1.031. 



OYSTERS AND METHODS OF OYSTER-CULTURE. 283 

which will be the reading of the scale nearest the point where the sur- 
face of the water touches the stem. For purposes of oyster-culture the 
finer graduations may be neglected. To show the specific gravity, the 
number "1.0" should always be placed in front of the scale reading; 
for example, if the surface of the water should stand opposite the scale 
reading "15," the density would be 1.015. The test should be made 
immediately after the water specimen has been collected and a reading 
of the thermometer should be taken at the same time. 

For practical purposes on the oyster-beds, a bottle or jar not less than 
10 inches deep may be used instead of the copper cup, and any ordinary 
thermometer may be used for obtaining the temperature. The cheap, 
wooden-cased instruments known as "bath thermometers" serve very 
well, as they have no metal parts to be corroded by the salt water. In 
most oyster regions the salinometer reading from 1.020 to 1.031 will 
not be necessary, as the density on the oyster-beds rarely falls within 
its range. 

The specimens of water should be from the bottom, or near it, and 
may be conveniently obtained by the following rough method: An 
empty jug or large bottle weighted and corked is lowered to the bottom 
by means of a line. The cork is then pulled out by jerking on a cord 
previously attached to it, the receptacle fills with a sample of water 
from or near the bottom, and if hauled rapidly to the surface it answers 
the practical purposes of more scientific and accurate apparatus. 

SILT, MUD, AND SUSPENDED MATTER. 

A bottom composed of soft mud, into which the young oysters would 
sink and become stifled, is unfavorable to oyster- culture or to the de- 
velopment of natural beds. If, however, hard objects are distributed 
over the bottom they will become collectors of spat so long as the 
surface remains clean and free from slime and sediment, and the 
importance of having water containing as little sedimentary matter 
as possible is manifest if it is desired to produce permanent beds or 
catch the floating fry. 

Oysters will grow more rapidly on muddy bottoms, or in their vicinity, 
than they will elsewhere, as such situations are usually more pro- 
ductive of food materials. This food is in the form of suspended or 
swimming organic particles, and, therefore, filtered water, or that which 
is devoid of suspended matter of all kinds, lacks one of the essential 
requirements of successful oyster-culture. The most desirable water 
is that which contains an abundance of minute living particles with a 
minimum of suspended inorganic matter. An organic slime, however, 
such as rapidly forms on exposed surfaces in some localities, is as 
effectual in preventing fixation as is inorganic sediment. In many 
places in Chesapeake Bay and in the bays on the New Jersey coast the 
sediment, as well as the bottom mud, is largely composed of the finely 
comminuted fragments of vegetable matter, seaweeds, etc., the rapid 
deposit of which soon covers with a soft film the surface of all objects 



284 REPOET OE COMMISSIONER OE FISH AND FISHERIES. 

exposed to it, except when the currents are sufficient to exert a scouring' 
influence. 

Large oysters are not so susceptible as small ones to the effects of 
mud, but even those full grown may be stifled or buried by the rapid 
deposit of mud or sediment, whether this be of organic or inorganic 
origin. Freshets and heavy seas often cause great damage by the 
amount of mud, sand, and other debris which they carry upon the beds. 

The question of the physical characters of a suitable bottom for 
oyster-culture is considered in another connection. 

TIDES AND CURRENTS. 

Tides and currents are important factors in the growth and culture 
of the oyster. They bring about the aeration of the water and oxida- 
tion of its dead organic ingredients; they have a scouring action upon 
the bottom and thereby cleanse the cultch, and at the same time serve 
as the vehicles for the transportation of food, of the genital products, 
and of the young. Stagnant water tends to become exhausted of its 
oxygen; it is heated by the sun, and the contained organic matter 
undergoing death and decomposition causes it to become foul and fatal 
to the oysters in the vicinity. With currents, however, a fresh supply 
of oxygen is constantly being supplied for respiration and for the 
combustion of the effete matter, which is thus rendered harmless. 

Over densely-populated beds the food supply, unless unusually pro- 
lific, as in claires, would in time become exhausted. The oyster can 
not, of course, change its location, but the same purpose is subserved 
by currents constantly bringing a fresh supply of food-laden water 
within the influence of the ciliary action by which the oyster captures 
its food. 

The genital products of the oyster, both male and female, are simply 
discharged into the surrounding water. The eggs are absolutely immo- 
bile, and while the spermatozoa, or male elements, possess the power of 
locomotion to some extent, they are obviously incapable of moving very 
far during the limited period of their mobility. In densely-crowded beds 
no doubt a considerable proportion of the eggs may become fertilized 
even without the agency of currents, but where, as upon most oyster- 
grounds, the oysters are scattered, the proportion must be exceedingly 
small. Oystermen are well acquainted with the fact that upon beds 
removed from the influence of the tides the rate of reproduction is 
very low. 

Currents, however, will bring about a distribution of the genital 
products, more particularly the almost impalpable milt, and thus give 
an opportunity for obtaining better results by increasing the chances 
for spawn and milt to come into contact. Although the young spat is 
a free-swimming organism, yet its powers are not sufficient to carry it 
to any great distance from its original source. It is transported mainly 
by tidal currents, and, as a general rule, the more widely distributed 
a given lot of spat, the greater is the number liable to become success- 



OYSTERS AND METHODS OF OYSTER-CULTURE. 285 

fully set. Currents, even of considerable strength, do not prevent the 
settling down of the larval oyster and its fixation upon a proper 
surface. 

In the preparation of this surface the currents are also effective, 
inasmuch as by their scouring action they prevent the deposit of sedi- 
ment and slime, which soon render collectors unsuitable for the fixation 
of the young oyster. Finally, where the fry are uniformly distributed 
in a body of water a collector placed in a current will collect more spat 
than one in quiet water, because a greater quantity of water and con- 
sequently a larger number of fry will be brought into contact with it. 
Points around which fry-charged water sweeps with sufficient velocity 
to prevent the deposit of sediment are good places for the location of 
collectors. 

Freshets, for several reasons, usually have a bad effect upon the 
oyster-beds. When the volume of fresh water is large, the oysters 
suffer from the decrease in the density. Large quantities of mud and 
sediment are brought down by the floods and often deposited on the 
beds, covering up the cultch and smothering the young spat, and, if 
the amount of sedimentation is very great, even injuring or killing 
the adults. 

DEPTH OF WATER. 

The vertical range of the cultivated oyster beds is from the shore 
line to a depth of 15 fathoms. In New Jersey, Chesapeake Bay, South 
Carolina, and other places, there are beds which are partially exposed 
at low water, while in Long Island Sound successful oyster- culture 
is carried on in depths as great as 15 fathoms, the average over planted 
grounds in that region, however, being from 5 to 6 fathoms. In most 
places, however, the planting is done in shallow bays and coves. 

WEATHER CONDITIONS — STORMS, GALES, AND ICE. 

Gales rarely have any influence upon adult oysters in deep water, 
but they sometimes seriously affect shallow-water beds. Heavy surf 
occasionally carries away the oysters and throws them upon the beach, 
or they may be buried in situ by the sand and seaweeds which the 
waves lodge upon the beds. Sometimes, after the lapse of a short time, 
the beds are again uncovered by the eroding effects of currents, but in 
many cases they are practically destroyed, both old and young being 
smothered by the overlying deposits. 

In winter, ice often grounds upon the beds during gales and does 
considerable damage. The oyster appears also to be temporarily 
affected by the mere freezing of the waters, and it is said that, in the 
Chesapeake, oysters on the deeper beds are more affected than those in 
shoal and brackish water, becoming dark, slimy, and worthless for the 
market. Ten days or a fortnight must elapse after the disappearance 
of the ice before they become again fit for use. 

The fry are more affected by the weather than are the adults. Dr. 
Ryder found that in the swimming stage they were killed by thunder- 



286 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 

storms, by cold rains, and by sudden falls in temperature, and the 
prevalence of such weather during the spawning season must have an 
important effect upon the set of spat. 

FOOD. 

The oyster feeds upon both animal and vegetable food, the particles of 
which are of microscopic dimensions. The fry and young spat consume 
relatively large quantities of bacteria and monads, among the most 
minute organisms known to microscopists. According to Dr. Eyder: 

Many of the food balls found in the intestine of the recently attached spat will 
measure under ttto^tt inch in diameter. The cavity of the little creature's stomach 
measures only ysvv inch. Yet in this minute digestive cavity the food is actually 
found rotating in the form of minute rounded and oval bodies, which are kept in 
motion by the action of the cilia which line the stomach. That these bodies must 
have been of about the size noted when they were originally swallowed and as seen 
rotating in the stomach is evident from the fact that the young oysters, like the 
adults, are wholly without teeth or triturating organs of any jjind. 

This minute kind of vegetable and animal food is found more or less abundantly 
in all sea water, and is especially abundant during the spawning season, when the 
decomposition and disintegration of all kinds of minute organic debris floating about 
in the water is in rapid progress, owing to the prevalent high temperature of the 
air and water. It is, therefore, probable that very few otherwise suitable locations 
exist where it is not possible to find an abundance of the proper sort of food for the 
oyster during its very earliest stages of growth. 

The food of the slightly more advanced spat and the adults is found to consist of 
diatoms, rhizopods, infusoria of all kinds, monads, spores of alga?, pollen grains 
blown from trees and plants on shore, their own larvae or fry, as well as that of many 
other mollusks, of bryozoa and minute embryos of polyps and worms, together with 
other fragments of animal or vegetable origin, and sometimes even minute crusta- 
ceans. In variety of food the oyster, therefore, has a wide range of choice. There 
are also few locations otherwise well adapted which will not supply an abundance 
of food for the animal, which, it is to be remembered, captures and hoards millions 
of these minute plants and creatures in its stomach, where they are digested and 
incorporated into its own organization. It therefore follows that when we eat an 
oyster we are consuming what it required millions of the minutest organisms in the 
world to nourish. The oyster is consequently a sort of living storehouse for the 
incorporation and appropriation of the minute life of the sea, which could never be 
rendered tributary to the food supply of mankind in any other way except through 
the action, growth, and organization of this mollusk.* 

The quantity of young oysters consumed by the adults is doubtless 
enormous, 200 fry having been found in the stomach of single individ- 
uals. Xot only the free-swimming fry, but eggs and spermatozoa are fed 
upon, and an insight Is here gained into the ultimate fate of some of the 
vast numbers of genital elements which the parents shed into the water. 

While the oyster feeds upon both plant and animal organisms, it 
must be remembered that it is primarily dependent upon the former. 
That not only is the major portion ol the food of the oyster itself of 
vegetable origin, but the minute animal forms are dependent for their 
sustenance upon the plants and are not to be found in abundance far 
removed from them. 

* Rept. U. S. F. C. 1885, pp. 387-388. 






OYSTERS AND METHODS OF OYSTER-CULTURE. 287 

In most regions which have been investigated the plants constitute 
by far the most important item of diet, usually over 90 per cent of the 
food contents of the stomachs being composed of vegetable matter. 
Of this diatoms are the chief constituents, and to a certain extent the 
food value of any given oyster region may be measured by the quantity 
of these minute plants which it is capable of producing. 

Diatoms are numerous both in species and individuals, and all possess 
two interesting peculiarities : They are incased in a siliceous or flinty 
box and they possess the power of locomotion, the first permitting their 
ready identification in the stomach contents and the second aiding in 
their distribution. More or less regular diurnal migrations of swarms 
to and from the surface of the water take place with the variations in 
the light. During sunlight they rise from the bottom, and are then 
readily transported by the currents, again settling down as darkness 
comes on. They feed and grow in size most actively during the day, but 
multiply in number principally at night. Diatoms are important, not 
only in fattening the oyster, but they also have a profound influence 
upon its flavor and color. 

The oyster is said to feed mainly during flood tide, opening its shell 
at that time to admit the influx of water with its contained organisms. 
Investigation by Dr. Bashford Dean showed that the stomachs were 
practically foodless in the morning, contained most food at midday, 
and a somewhat reduced quantity at evening, thus suggesting that 
feeding was most active during intense daylight. 

Dr. Dean remarks : 

This suggestion, as to the feeding habits of the oyster, is not a surprising one 
when we remember that it is during the strongest sunlight than diatoms, as plants 
keenly sensitive to the sun, are most active and are known to migrate in floating 
clouds from the bottom of the surface. 

As is mentioned in the section relating to the anatomy of the oyster, 
the water drawn into the mantle cavity by the action of the cilia is 
filtered through the rectangular openings in the gills into a chamber or 
tube lying above each gill, whence it passes backward and out of the 
shell in a current dorsal to the entering stream. The particles of food 
in the inflowing stream become entrapped in a sticky mucus covering 
the gills, and, together with this mucus, in part, are carried in a steady 
stream toward the mouth, the motion being imparted to the mass by 
the rhythmic action of the cilia. The palps and mouth are also 
ciliated, which insures the continuance of this current into the stomach, 
where the food particles undergo digestion. A very considerable pro- 
portion of inert matter, sand, mud, etc., of no nutrient value passes into 
the alimentary tract along with the food, the oyster having no means 
of making selection. 

The temperature, depth, and density of the water have considerable 
effect upon the food supply. In clear, warm weather the amount of 
food matter is increased by the natural multiplication of the minute 



288 REPORT OF COMMISSIONER OP PISH AND FISHERIES. 

organic bodies which find such conditions favorable, but at the same 
time many of these organisms, particularly the diatoms and zoospores, 
are attracted to the surface by the sunlight and are thus placed beyond 
reach of the oyster. In rainy or stormy weather, however, they are 
driven down toward the bottom, where they may be brought within the 
influence of the cilia, and at the same time there is an increase in the 
amount of other organic sediment, much of which is available as food. 

Shallow water, as a rule, produces more food than the greater 
depths, owing largely to the fact that it warms more quickly and thus 
increases the vitality of both the oyster and its food. The latter shows 
its greater vigor by a more rapid multiplication, and the former by its 
greater consumption of the food which is thus provided for it. In other 
words, the chemical and physiological changes resulting in the conver- 
sion of inorganic matter into oyster tissue through the medium of plant 
life go on more rapidly in the presence of warmth. It must also be 
remembered that the shallow waters are generally of a lower density 
than the deeper ones, and this approach to brackishness appears to be 
also favorable to the production of food. 

Summer and fall, the seasons of most vigorous growth of aquatic 
vegetation, are in most localities likewise the best seasons for the 
growth of the oyster, while in winter the food supply is at a minimum, 
the vital activities of the oyster are much reduced, the ciliary action is 
weak, and the oyster in a state of semihibernation, both the waste and 
repair of tissue being reduced to a minimum. 

That the oyster in many places reaches its greatest fatness and per- 
fection late in fall is due partly to the quantity of food produced during 
the summer and partly to the cessation of the drain which the act of 
spawning entails. Shortly before and during the spawning season 
most of the nutrient matter in the food is utilized in the rapid growth 
of the sexual products, but after the cessation of spawning it is con- 
verted into surplus protoplasmic matter, which is stored up in the 
tissues and thereby renders the oyster fat and well flavored. 

ENEMIES. 

At all stages of its career the oyster is preyed upon by more or less 
dangerous foes. It might be supposed that an animal inclosed in a 
ponderous armor, which in times of danger is a complete encasement, 
would be free from the attacks of enemies, but no organism has ever 
evolved a protective device which some other organism has not found 
partially vulnerable; and it must be remembered that the oyster is not 
always as well protected as we find it in the adult and marketable con- 
dition. In the young state, before attachment, the minute and delicate 
fry is fed upon extensively by the adult oyster and by other mollusca, 
lingulas, worms, sponges, and hydroids. Upward of 200 young have 
been found in the stomach of an oyster, and there is but little doubt 
large numbers are so consumed on ev.ery oyster-bed. Probably the 



OYSTERS AND METHODS OF OYSTER-CULTURE. 289 

■ 
menhaden, the ale wife, and other fish equipped with delicate sifting 

devices at times find the oyster fry of some importance in their dietary. 

After the attachment of the spat other enemies, active and passive, 
wage war upon it. The passive enemies affect its welfare by consum- 
ing its food or by smothering it beneath their own more active growth. 
Of the former class, mussels, lingulas, etc., are examples, but as the 
food upon an oyster-bed is usually sufficient for all, this is not a very 
important consideration, particularly as in the end an equilibrium is 
established through the intimate reciprocity which exists between the 
various forms of life. 

The conditions of life upon an oyster-bed are favorable to the rapid 
growth of dense sponges, mussels, barnacles, hydroids, and tube-build- 
ing worms, which establish themselves upon tne young growth, often 
increase more rapidly than their hosts, and, in many cases, overgrow 
them to such an extent as to cut off the supply of food and oxygen. 
(Plate xvu). Aquatic vegetation sometimes has the same effect when 
its growth becomes extensive. Certain worms, such as Serpula, and 
especially Sabcllarla (plate xv, fig. 3), often build their tubes of lime or 
sand so rapidly as to produce dense accumulations upon the surface 
of the shells, thus forming a nidus for the collection of sand and mud. 
Considerable loss has at times resulted from the suffocation of oysters 
by sponges, worm tubes, and vegetable growths, but most of these 
passive forms have a compensatory use in the food which their spores, 
eggs, and young furnish to the oysters. 

The active enemies of the adult oyster are those which injure it by 
direct attacks, such enemies being found in most of the classes of 
zoological life having aquatic representatives. 

Fishes of several kinds are found habitually on the oyster-beds. 
Most of these offer no direct injury and they may even benefit the 
oyster by keeping down the crowding masses of hydroids and vegetable 
life, but a few species, of which the drumfish is apparently the most 
destructive upon the Atlantic coast, consume considerable quantities 
of oysters as food. At times much damage has thus been wrought to 
the beds in the vicinity of New York and along the New Jersey coast. 
In San Francisco Bay the stingray is the most feared enemy of the 
oyster, and schools of them frequently "clean out" the beds to which 
they gain access, their teeth being such that the shells are crushed into 
fragments in their grasp. Some of the skates aud rays on the eastern 
coast no doubt have similar habits, but they do not appear in sufficient 
numbers to cause much harm. 

The drills are the most destructive enemies of the oysters in the 
Chesapeake and adjoining regions, as well as upon most of the more 
important inshore beds northward. There are, perhaps, several species, 
but the most destructive is the form known to naturalists as Urosalpinx 
cinerea (jdate xv, fig. 1). It is a snail-like mollusk, which, by means of its 
rasping tongue, drills a tiny hole in the shell of the oyster, through which 
it extracts the soft parts. It is only the younger oysters which are thus 

F. C. E. 1897 19 



290 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 

attacked, as after they become about 2 inches long the shell is stout 
enough to resist this foe. The loss sustained from this source is very 
great, as the drills are often present in large numbers and continue 
their work throughout the year. 

The two large conch-like gasteropods of the Atlantic coast, Sycoty- 
pus canaliculatus and Fulgur carica (plate xv, fig. 4), also feed upon the 
oyster, from their size being capable of attacking the largest individ- 
uals. These periwinkles, "winkles," or conchs, as they are variously 
called, appear to do comparatively little damage, as they are not pres- 
ent in sufficiently large numbers anywhere except perhaps on the coast 
of Florida. 

Other gasteropods doubtless feed upon the oyster, but not to an 
extent worthy of consideration. 

Upon brackish-water beds the starfish (plate xvi) is not usually 
troublesome, and in Chesapeake Bay it is practically unknown, but in 
Long Island Sound, and especially upon the offshore beds in the more 
saline waters, it is the most destructive enemy with which oystermen 
have to contend. It is there extremely abundant at times, but it is a 
migratory form, and sometimes certain beds are unmolested while others 
nearby are almost ruined by its inroads. The appearance of this pest 
upon the beds is without warning, and frequently the ground is almost 
devastated before the owner is aware of their presence. Yast swarms 
or schools sweep across the beds, devouring the oysters in their path. 
The migration is said to take place in the form of a "winrow," moving 
in some cases at the rate of about 500 feet per day. Apparently the 
only way to stop the march of these hordes is to catch them up by some 
of the methods indicated in pp. 313-31(3. By energetic work the damage 
may often be confined to the beds at the edge of a cultivated area. 

The starfish begins its destructive work soon after it abandons its 
free-swimming larval condition, at a time when it is hardly larger than 
a pin's head, and continues it through life. At first it feeds upon the 
fciny spat, but as it grows it increases the size of its prey, though even 
the full-grown stars rarely feed upon oysters over two, or, at most, 
three years old. Small oysters are often taken bodily into the stomach 
of the starfish, a proceeding which is of course impossible with large 
ones or those firmly attached to large cultch. It is not definitely known 
how the oysters are opened, but Dr. Paulus Schiemenz has pretty con- 
clusively demonstrated the probability that they are actually pulled 
open by muscular effort on the part of the starfish. 

If the coimmoiii starfish be examined there will be found on the under 
surface of each arm four rows of closely crowded suckers or feet extend- 
ing from the mouth to the tips of the arms. These feet are tubular 
and are extended by having a fluid pumped into their cavities by a 
special apparatus in the body of the starfish. The suckers at the ends 
may be caused to adhere to foreign bodies with great tenacity, and if 
the hydrostatic pressure be then relieved and the muscles of the stalks 
of the feet contract, a strong pull may be exerted by each foot, either 



OYSTERS AND METHODS OF OYSTER-CULTURE. 291 

independently of its fellows or in conjunction with them. As shown 
in plate xvi, the starfish feeding upon oysters or other lamellibranchs 
arches itself over the nibs or lips of the mollusk so that some of its arms 
are on one side and some on the other. In this position a large number 
of the sucker feet are attached to each valve, and when they contract 
a stress is produced in opposite directions and opposed to the force of 
the adductor muscle which tends to keep the valves of the oyster 
closed. Dr. Schiemenz has shown by actual measurement that in this 
manner there is exerted a force sufficient to overcome any resistance 
which the oyster may offer. It is eventually tired out by the persist- 
ence of its enemy, its shell is forced open, the stomach of the starfish 
is inserted, and within a few hours the valves only remain. 

Another annoying and frequently very destructive enemy of the 
oyster is the boriug-sponge, Cliona sulphured. It differs from the 
enemies before enumerated in that it consumes the shell and not the 
soft parts of the unfortunate oyster. The young sponge lives in galleries 
excavated in the substance of either dead or living shells which are 
soon reduced to a honey-combed condition, when they may be crumbled 
to powder between the fingers. When they attack a living oyster, 
as the galleries penetrate the inner face of the shell, an irritation of 
the mantle is produced, causing an increased amount of shell deposit 
at that point. If the inside of such a shell be examined it will be found 
to be covered with blister-like shell deposits, sealing up the openings to 
the galleries, and many curious distortions follow from the destruction 
of the hinge area and the portion of the shell to which the adductor 
muscle is attached. Although the oyster itself is not attacked, yet it 
becomes poor, thin, and watery and often dies from the exhaustion 
induced by the constant effort to keep its shell intact. 

The older specimens of the boring-sponge are large, dense, yellow 
masses, often 6 or 7 inches in diameter and usually inclosing the shells, 
etc., to which they were originally attached. All stages intermediate 
between those described can usually be found upon infested oyster- 
beds. The older, more massive forms often suffocate the oyster through 
the denseness of their growth. 

In addition to the various forms already enumerated there is a large 
population upon the oyster-beds which is not injurious. This, of course, 
includes many of the minute food forms, together with some of the fishes 
and crabs. The latter, at least on the Atlantic coast, can not be 
regarded as very destructive, but on the contrary they serve as scav- 
engers, removing dead matter trom the beds when it might otherwise 
become foul and fatal to the oysters. It will be seen that the popula- 
tion of the oyster-beds is large and extremely complex. The social 
relations of the various forms are exceedingly intricate and have, in 
the course of evolution, become nicely adjusted in a system of reciprocity. 
The law of the oyster beds is "give and take," each of a large number 
of organisms giving something for the general welfare and taking what 
it needs for its own well being. 



292 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 

DESCRIPTION OF NATURAL BED. 

Dr. Brooks thus describes a natural oyster bank: 

An examination of a Coast Survey chart of any part of the Chesapeake Bay or ofi 
any of its tributaries will show that there is usually a midchaunel or line of deep 
water where the bottom is generally soft and where no oysters are met with, and on 
each side of this an area where the bottom is hard, running from the edge of the 
channel to the shore. This hard strip is the oyster area. It varies in width from a 
few yards to several miles, and the depth of water varies upon it from a few feet to 
5 or 6 fathoms or even more. But there is usually a sudden fall at the edge of the 
channel where the oysters stop, and we pass onto hard bottom ; and a cross-section 
of the channel would show a hard, flat plane with oysters on each side of the deep, 
muddy channel. The oyster bottom is pretty continuous, except opposite the mouth 
of a tributary, where it is cut across by a deep, muddy channel. The solid oyster 
rocks are usually situated along the outer edge of this plateau, although in many 
cases they are found over its whole width nearly up to low-tide mark or beyond. 
As we pass south along the bays and sounds of Virginia and North Carolina, we nnd 
that the hard borders of the channel come nearer and nearer to the surface until in 
the lower part of North Carolina there is on each side of the channel a wide strip of 
hard bottom, which is bare at low tide and covered with oysters up to high-water 
mark, although the oysters are most abundant and largest at the edge of the deep 
water, where they form a well-defined reef. In our own waters there is usually a 
strip along the shore where no oysters are found, as the depth of water is not great 
enough to protect them in winter. The whole of the hard belt is not uniformly 
covered with oysters, but it is divided up into separate oyster rocks, between which 
comparatively few can be found. 

The boundaries of a natural rock which has not been changed by dredging are 
usually well defined, and few oysters are to be found beyond its limits. The oysters 
are crowded together so closely that they can not lie flat, but grow vertically upward, 
side by side. They are long and narrow, are fastened together in clusters, and are 
known as "coon oysters." 

When such a bed is carefully examined it will be found that most of the rock is 
made up of empty shells, and a little examination will show that the crowding is so 
great that the growth of .one oyster prevents adjacent ones from opening their shells, 
and thus crowds them out and exterminates them. Examination shows, too, that 
nearly every one of the living oysters is fastened to the open or free end of a dead 
shell which has thus been crowded to death, and it is not at all unusual to find a 
pile of five or six shells thus united, showing that number two has fastened, when 
small, to the open end of number one, thus raising itself a little above the crowd. 
After number one was killed, number two continued to grow, and number three fast- 
ened itself to its shell, and so on. Usually the oysters upon such a bed are-small, but 
in some places shells 12 or 14 inches longiareimot with. The most significant charac- 
teristic of a bed of this kind is the sharpness of its boundaries. In regions where 
the oysters are never disturbed by man it is not unusual to find a hard bottom 
extending along the edge of the shore for miles and divided up into a number of 
oyster rocks, where the oysters are so thick that most of them are crowded out and 
die long before they are full grown, and between these beds are areas where not a 
single oyster can be found. The intervening area is perfectly adapted for the oyster, 
and when a few bushels of shells are scattered upon it they are soon covered with 
young, and in a year or two a new oyster rock is established upon them, but when 
they are left to themselves the rocks remain sharply defined. 

What is the reason for this sharp limitation of a natural bed? Those who know 
the oyster only in its adult condition may believe that it is due to the absence of 
powers of locomotion and may hold that the young oysters grew up among the old 
ones, just as young oak trees grow up where the acorus fall from the branches. This 
can not be the true explanation, for the young oysters are swimming animals, and 



OYSTERS AND METHODS OF OYSTER-CULTURE. 293 

they are discharged into the water in countless numbers, to be swept away to great 
distances by the currents. As they are too small to be seen at this time without a 
microscope it is impossible to trace their wanderings directly, but it is possible to 
show indirectly that they are carried to great distances and that the water for miles 
around the natural bed is full of them. They serve as food for other marine animals, 
and when the contents of the stomachs of these animals are carefully examined with 
a microscope the shells of the little oysters are often found in abundance. While 
examining the contents of the stomach of lingula in this way I have found hundreds 
of the shells of the young oysters in the swimming stage of growth, although the 
specimens of lingula were captured several miles from the nearest oyster-bed. As 
lingula is a fixed animal the oysters must have been brought to the spot where the 
specimens were found, and as the lingula has no means of capturing its food, and 
subsists upon what is swept within its reach by the water, the presence of so many 
inside its stomach shows that the water must have contained great numbers of them. 

It is clear, then, that the sharp limitation of the area of a natural oyster bed is not 
due to the absence in the young of the power to reach distant points. There is 
another proof of this, which is familiar to all oystermen — the possibility of estab- 
lishing new beds without transplanting any oysters. The following illustration of 
this was observed by one of your commissioners : On part of a large mud flat which 
was bare at low tide there were no oysters, although there was a natural bed upon 
the same flats, about half a mile away. A wharf was built from high-tide mark 
across the flat out to the edge of the channel, and the shells of all the oysters which 
were consumed in the house were thrown onto the mud alongside the wharf. In the 
third summer the flat in the vicinity of the wharf had become converted into an 
oyster-bed, Avith a few medium-sized oysters and very great numbers of young, and 
the bottom, which had been rather soft, had become quite hard; in fact, the spot 
presented all the characteristics of a natural bed. Changes of this sort are a 
matter of familiar experience, and it is plain that something else besides the absence 
in the oyster of locomotive power determines the size and position of a bed. 

Now, what is this something else? If the planting of dead shells will build up a 
new bed, may we not conclude that a natural bed tends to retain its position and 
size because the shells are there? This conclusion may not seem to be very import- 
ant, but I hope to show that it is really of fundamental importance and is essential 
to a correct conception of the oyster problem. 

Why should the presence of shells, which are dead and have no power to multiply, 
have anything to do with the perpetuation of a bed? 

We have already called attention to the fact that oysters are found on the hard 
bottom on each side of the channel, while they are not fouud in the soft mud of the 
channel itself, and it may at first seem as if there were some direct connection 
between a hard bottom and the presence of oysters, but the fact that no oysters are 
found upon the hard, firm sand of the ocean beach shows that this is not the case. 
As a matter of fact, they thrive best upon a soft bottom. They feed upon the floating 
organic matter which is brought to them by the water, and this food is most abun- 
dant where the water flows in a strong current over soft organic mud. When the 
bottom is hard there is little food, and this little is not favorably placed for diffusion 
by the water, while the water which flows over soft mud is rich in food. 

The young oysters which settle upon or near a soft bottom are therefore most 
favorably placed for procuring food, but the young oyster is very small — so small 
that a layer of mud as deep as the thickness of a sheet of paper would smother and 
destroy it. Hence the young oysters have the habit of fastening themselves to solid 
bodies, such as shells, rocks, or piles, or floating bushes, and they are enabled to 
profit by the soft bottoms without danger. 

Owing to the peculiar shape of an oyster shell, some portions usually project above 
the mud long after most of it is buried, and its rough surface furnishes an excellent 
basis for attachment. It forms one of the very best supports for the young, and a 
little swimming oyster is especially fortunate if it finds a clean shell to adhere to 
when it is ready to settle down for life. Then, too, the decaying and crumbling 



294 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 

shells are gradually dissolved in the sea water, and thus furnish the lime which the 
growing oyster needs to build up its own shell. As long as the shell is soft and thin 
the danger from enemies is very great, and this danger is greatly diminished as 
soon as the shell becomes thick enough to resist attack. It is, therefore, very neces- 
sary that the shell should be built up as rapidly as possible, and an abundant supply 
of food in general will be of no advantage unless the supply of lime is great enough 
for the growth of the shell to keep pace with the growth of the body. All sea 
water contains lime in solution, but the percentage is, of course, greatest near the 
sources of supply. It is well known that on coral reefs, which are entirely made of 
lime, all kinds of shelled mollusks flourish in unusual abundance and have very 
strong and massive shells, and our common land and fresh- water snails are much 
larger and more abundant in a limestone region than in one where the supply of 
lime is scanty. In such regions it is not unusual to find the snails gathered around 
old decaying bones, to which they have been drawn in order to obtain a supply of 
lime for their shells. 

From all these causes combined it results that a young oyster which settles upon a 
natural oyster-bed has a much better chance of survival than one which settles 
anywhere else, and a natural bed thus tends to perpetuate itself and to persist as a 
definite, well-defined area ; but there is still another reason. As the flood tide rushes 
up the channels it stirs up the fine mud which has been deposited in the deep water. 
The mud is swept up onto the shallows along the shore, and if these are level much of 
the sediment settles there. If, however, the flat is covered by groups of oysters, the 
ebbing tide does not flow off in an even sheet, but is broken up into thousands 
of small channels, through which the sediment flows down to be swept out to sea. 

The oyster-bed thus tends to keep itself clean, and for these various reasons it 
follows that the more firmly established an oyster bed is the better is its chance of 
perpetuation, since the young spat finds more favorable conditions where there are 
oysters, or at least shells, already than it finds anywhere else. 

Now, what is the practical importance of this description of a natural bed ? It is 
this: Since a natural bed tends to remain permanent, because of the presence of 
oyster shells, the shelling of bottoms where there are no oysters furnishes us with a 
means of establishing new beds or of increasing the area of the old ones. 

The oyster-dredgers state, with perfect truth, that by breaking up the crowded 
clusters of oysters and by scattering the shells the use of the dredge tends to enlarge 
the oyster-beds. The sketch which we have just given shows the truth of this claim, 
but this is a very rough and crude way of accomplishing this end.* 

This description, so far as it relates to the oysters themselves, gives 
a good idea of the average oyster-bed, though they differ somewhat in 
details in different localities. But, as shown in the sections which treat 
of the enemies and the food of the oyster, the latter is very far from 
constituting the entire population of the beds. The same causes which 
induce the growth of the oyster, the firm basis of attachment, the sur- 
rounding food-producing mud, the favorable density and temperature, 
all tend to make the oyster-bed a center teeming with aquatic life. 
Thus a single point of attachment, a firm nucleus projecting naturally 
above the surrounding mud, or a few shells thrown upon the muddy 
bottom may give rise to a community where life is as abundant and the 
struggle for existence as complex and strenuous as is anywhere found 
in nature. 

* Brooks, W. K., Maryland Oyster Report, 1884, pp. 86 to 88, inclusive. 



OYSTERS AND METHODS OF OYSTER-CULTURE. 295 

DESTRUCTION OF NATURAL BEDS— CAUSES AND REMEDIES. 

Until a comparatively recent date our supply of oysters was drawn 
almost entirely from the natural beds, which were originally so vast that 
it was a common saying that they were inexhaustible. The fallacy of 
this view has been abundantly proven, and wherever reliance has been 
placed upon natural beds solely there has been a decreasing supply to 
meet an increasing demand. Many causes have been cited to account 
for the decrease in the productiveness of the oyster-beds, but wherever 
unprejudiced investigation has been brought to bear upon the subject 
the verdict has always been that the fishing upon the beds has outgrown 
their fecundity. 

Vast as is the production of spawn, the chances against its growth 
to maturity are such as to limit the productiveness of the beds. Much of 
it fails of fertilization. Most which passes that critical stage becomes 
a prey to enemies or falls upon unsuitable bottom, where it fails of 
attachment and sinks in the ooze. Even after the vicissitudes of 
larval life are passed the infantile spat may be buried in an accumu- 
lation of organic or inorganic sediment, or it may be devoured by 
enemies against which it can present no adequate defense. Storms 
may tear the adult oysters from their attachment and cast them upon 
the shore, or they may become covered by sand and seaweeds drifted 
in by the waves; or, again, excessively cold weather may cause their 
death in exposed places by freezing. 

Numerous as are the perils which beset them under their natural 
surroundings, they have, upon the whole, found the conditions favorable 
for their maintenance and increase until civilized man began his syste- 
matic attacks. It is true that before the appearance of the white man 
upon the scene they had disappeared from regions where they were 
formerly found, but upon our coasts such cases are isolated and rare. 

Without here going into the evidence, it may be asserted as a dem- 
onstrated fact that overfishing is the cause of the depletion of our 
oyster-beds, and that it produces its damaging effect in several ways: 

1. It removes the adult oysters, which are either spawning or are 
capable of spawning, and thereby reduces the reproductive power of 
the bed as a whole. 

2. It removes the shells, and therefore decreases the available points 
of attachment of the spawn. When the oysters are not culled on the 
beds this effect is aggravated by the removal of the dead shells. 

3. Spat and young oysters attached to the shells of the adults are 
removed from the beds, and as it is impracticable in many cases to 
detach them they are of necessity destroyed. 

4. The quantity of oysters taken and destroyed from the several 
causes mentioned is greater than that which is permitted to annually 
grow up to take their places. 

Many causes have been assigned as tending to deplete the oyster- 
beds, and many remedies have been proposed. Various phases of the 



296 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 

oyster business have been cited to show cause why they should not be 
curtailed or abolished as destructive. It has been proposed to restrict 
the demand by prohibiting canning; to prohibit the use of this or that 
kind of apparatus, or to interfere in various ways, with more or less 
legitimate methods of meeting and increasing the demand. 

r .L'he attempts that have been made to keep the demand upon the beds 
within the limit of their fecundity have so far been failures, and such 
attempts are also seen to be illogical when it can be shown that the 
reciprocal measure, increasing the supply, is perfectly feasible. 

The dictates of sound economics require that no effort be made to 
restrict the demand until it can be shown that efforts to increase the sup- 
ply are futile. A growing demand for a product is the most trustworthy 
indication of an industry's prosperity, and the only rational manner in 
which to bring the supply and demand into equilibrium is to increase 
the former. Only after the failure of all efforts to save the supply from 
total extinction, should a restriction be placed upon the demand. 

The close season has been a favorite measure in protective legisla- 
tion, as it has been in most legislation looking to the perpetuation of 
game and fish. It is usual to fix the close season during the spawning 
months, upon the theory that the reproductive act should be allowed 
to proceed unmolested. It really matters but little whether the oyster 
is taken during the season of spawning or a month or two before; the 
effect upon the fishery is the same, as in either case the bed is deprived 
of an individual capable of reproducing its kind. The only effect of a 
close season, whenever occurring, is to reduce the time during which 
the oyster is subject to attack from the oystermen. Even this is of 
little avail with the sedentary oyster, for it is possible for 365 men, 
fishing ten days, to as effectually "clean up 7 ' a bed as can be done by 
10 men fishing throughout the year. This has been found to be the 
practical result of a close season in some places; the first few days of 
fishing removing so many oysters as to make it unprofitable to work 
the beds during the rest of the year. 

The methods by which the increased demand resulting from a widen- 
ing of the markets may be met will be treated of in another connection. 
It may become necessary in some parts of this country, as in Europe, 
to reserve the natural beds for the production of seed. Such a reser- 
vation would naturally excite the strenuous opposition of the oystermen ; 
but should the industry ever be reduced to the desperate condition at 
one time found in France, correspondingly desperate remedies must be 
invoked. 

INCREASE OF SUPPLY BY ARTIFICIAL MEANS. 

In many countries in which oysters are an important item of food it 
has been found necessary to give nature some assistance in order to 
maintainor increase the supply of oysters available for the markets. 
The direction in which this as sistance is rendered is governed by local 
conditions, but in general it may be stated that all methods of oyster- 
culture depend for their success upon the modification of the natural 



OYSTERS AND METHODS OF OYSTER-CULTURE. 297 

conditions in such a manner as to bring about one or several of the 
following results : 

1. An increase in the number of eggs successfully fertilized. 

2. An increase in the surfaces available for fixation, and consequently 
an increase in the number of spat which become fixed and pass through 
the early stages of spat existence. 

3. The utilization and salvage of spat, which would otherwise fall 
victims to the several vicissitudes of their careers — storms, frosts, 
crowding, etc. 

4. A decrease in the liability to attacks from enemies. 

5. The utilization of otherwise neglected bottoms and food supplies. 
Upon our coasts the objects set forth above, or some of them, have 

been best realized by the process of " planting." This consists in 
placing firm bodies in the water for the purpose of catching the spat 
or in spreading young oysters upon the bottom in places suitable for 
their growth. Vast as are our oyster-fields, but a small portion of the 
bottom available for the growth of this mollusk has been utilized by 
nature. This has arisen from the fact that in many cases where the 
other conditions are favorable the bottom is of such a character as to 
prevent the attachment of the young, though perfectly adapted to the 
rapid growth of the adults. If then the spat be caught on planted 
cultch, or partially grown oysters be placed upon such bottoms, the 
difficulty is overcome and nature has been assisted to the degree 
necessary and all or some of the conditions mentioned above are more 
or less completely fulfilled; the first by increasing the number of 
adult oysters in any region, and by their closer aggregation ; the second, 
by the process of preparing the ground and sowing the shells; the 
third, by the use of seed from regions less favorable to its maturing; 
the fourth, from the greater care with which a bed under private owner- 
ship will be watched and guarded, and the fifth by the very act of 
planting upon virgin or depleted bottom. 

Other and more complex plans of oyster-culture are employed in the 
countries of Europe, but have not yet been adopted in the United 
States. There are indications, however, that in certain portions of our 
oyster belt it may be necessary to follow some method of pond culture, 
not so much for the purpose of growing the oysters, but to fatten them 
for market. Should the feasibility of this be demonstrated under the 
conditions prevailing in the United States, a vast increase could be 
made to our oyster supply, as it is a well-known fact that certain large 
areas are capable of raising oysters which they rarely fatten and for 
which, therefore, no market can be found. 

By some modification of pond culture it may also be possible to 
raise seed oysters in regions in which few or none are now produced, 
thus adding another considerable item to the wealth-giving powers of 
our coasts. 

These several subjects are treated under their appropriate headings 
in the following pages. 



298 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 

PLANTING WITH SEED. 
PRELIMINARY CONSIDERATIONS. 

Preliminary to planting, the first essential is to determine whether 
private rights in oyster bottoms are recognized by law or countenanced 
by public opinion. Unless the planter is assured of exclusive owner- 
ship in the product of his labor and enterprise he will find more profit 
and peace of mind in devoting his energies to some other calling. 
Unless the law, backed by the public sense of justice, makes the theft 
of oysters from planted grounds punishable like theft of any other 
kind, it will be impossible to expect success in oyster-planting. Very 
remarkable views obtain in some places concerning the right to property 
beneath the sea, and in such places the planter will find it impossible 
to protect his interests. 

Having determined that his rights in his riparian property may be 
successfully maintained, the next step is to select beds that present the 
proper conditions of temperature, density, bottom, food, etc. 

Temperature. — If it is desired to establish a self-perpetuating bed 
the temperature should rise for a considerable time during the spawn- 
ing period to between 68 and 80 degrees. If it be desired to merely 
increase the size of seed oysters obtained elsewhere, it is not necessary 
that the temperature should ever rise so high, although, as a rule, 
warm waters induce more rapid growth. The range of temperature to 
which adult oysters are subject will be seen on page 280. 

Density. — The density should be above 1.007 at least, and the beds 
should be so located as not to be subject to the influence of freshets 
which would reduce the density below that degree for any length of time. 
A density over 1.023 is not advisable, although oysters grow in places 
in a somewhat greater salinity. (See p. 281.) 

Bottom. — The character of the bottom is the most important consid- 
eration, and it is probable that, upon our coasts, the other conditions 
will be fairly met in any locality where suitable bottom is available. 
The selection should be made with care, and the methods employed 
should be adapted to the character of the ground. Otherwise the 
planter may be put to labor and expense without return. 

Hard, rocky bottom is in general uusuited for the cultivation of the 
oyster. Such ground, while affording facilities for the fixation of spat, 
does not supply sufficient food to cause a rapid growth, such as is desired 
by the planter, unless there is abundant muddy bottom in the vicinity. 
Heavy clay is open to the same objection. Loose sand is liable to drift 
and bury the oysters, and deep, soft mud is absolutely fatal, as it allows 
even adult oysters to sink to such a depth that they are smothered. 

The best bottom consists of a firm substratum, above which is a layer 
of soft flocculent mud. In Long Island Sound, firm, sandy bottom is 
often used with great success. The oysters do not grow so rapidly 
there, however, as they do upon the soft mud of Jamaica Bay and other 
places on the south shore of Long Island. 



OYSTERS AND METHODS OF OYSTER-CULTURE. 299 

Food. — The question of food is a sine qua non in oyster-culture. 
Without a supply of suitable and proper food it is useless to attempt the 
growth of oysters. As a general rule, it will be found that where the 
proper conditions of temperature obtain the vicinity of a muddy bottom 
will be well stocked with the minute organisms upon which the oyster 
'feeds. Reliance upon this fact, however, is placing dependence upon a 
"rule of thumb," never a profitable method where more accurate and 
scientific information can be obtained. Oystermen usually determine 
the best growing and fattening grounds by actual experiment, a pro- 
ceeding often entailing the wasteful expenditure of time and capital, 
and the small cost which would be involved in making a preliminary 
biological survey would be, in most cases, well expended. The currents 
may be such as to carry the food organisms away, or for other reasons 
beds, apparently well situated, may be lacking in food, a fact usually not 
discovered until time and money have been wasted in experimental 
planting. 

Marking bed, etc. — The boundaries of the planting-grounds should be 
marked with stakes in such a way that each planter will have no diffi- 
culty in distinguishing his own ground from that of his neighbor. In 
order to recover the boundary, should the stakes be carried away by 
storms or ice, it is usual to have ranges locating the most important 
marks, such as those at the corners of the beds, these ranges being 
either conspicuous natural objects, buildings, etc., or, preferably, signals 
erected especially for the purpose. In deep water, or upon bottoms 
where stakes can not be driven or held, buoys are commonly used for 
locating the beds. Some of the States have laws regulating more or 
less strictly the manner of describing and marking the private oyster- 
grounds, and to avoid trouble and disputes these should be strictly 
complied with. 

It should be remembered that it is more difficult to lay out and mark 
areas beneath the water than upon the land. It sometimes happens 
that the planter is able to get control of an entire cove or brackish- 
water creek, in which case the question of marking the beds and of 
protecting them from poachers is much simplified. In some places it is 
customary for owners to subdivide their beds for purposes hereafter 
mentioned, and such subdivisions may be marked in the manner adopted 
for indicating the boundary of the right. 

PREPARING BOTTOM. 

Having located and marked the beds, the ground should be prepared 
for planting. In places such as San Francisco Bay, where the oysters 
are placed on beds which are more or less exposed at low tide, this 
usually consists of clearing away the snags and other debris at low 
water and leveling off the mounds and filling up the hollows. If it is 
necessary to build stockades to protect the oysters from fish, this should 
also be done before planting is begun, as otherwise the bed may be 
ruined before it is fairly planted. 



300 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 

In deeper water the clearing up of the grounds is usually done by 
means of the dredge, all debris being carefully removed. This work is 
best performed by steam, the larger planters owning vessels and the 
smaller ones hiring them for the purpose. The work with sailboats is 
more laborious and less rapid. 

If the bottom is firm, or if there is a firm substratum an inch or two 
below the soft surface-layer, no further preparation is needed. When 
there is a soft mud of some depth, however, it is absolutely necessary 
that the surface be prepared in some way which will prevent the oysters 
from becoming completely submerged and suffocated in the soft deposit. 
This is usually done by distributing over the soft places various hard 
substances, which, resting upon the mud, give it a firm surface upon 
which the oysters may repose in safety. 

In France, where the lack of suitable grounds frequently requires 
the use of very soft bottoms, this difficulty is sometimes overcome by 
the expensive means of macadamizing the bottom with gravel and 
clay. While this, of course, forms an excellent bottom, hard and 
smooth, it can only be used on grounds exposed at low tide. 

American planters usually provide a firm surface by strewing oyster 
shells, clam shells, gravel, or sand over the bottom in such quantities 
as to have the desired effect. When shells or gravel are used the double 
purpose is often served of preventing the submergence of the adult 
oyster in the mud and offering a place of attachment for the spat. In 
certain places sandy and gravelly material resulting from dredging for 
harbor improvements has been utilized for this purpose, and much soft 
bottom, before valueless, has been made to yield a profitable return to 
the planter. Such material can often be obtained at a very small cost, 
sometimes merely for the expense of transportation to the beds. 

In surfacing, care should be exercised that the firm layer be deposited 
uniformly, as otherwise the muddy bottom will be exposed in places 
and the oysters falling thereon in planting will be engulfed in the mud. 
Plenty of material should always be used, as it is poor economy to 
spend money for work and material which is insufficient to accomplish 
the end sought. The exact amount necessary will depend upon the 
character of the bottom. Where it consists of a very deep, pulpy or 
flocculent deposit it is useless in most, cases to attempt to improve it, 
as the surfacing material will sink almost as fast as it is deposited. 
In places perhaps this might be overcome by the French system of 
macadamizing, but as more suitable bottom is abundant on our coast 
such an expensive procedure would be unnecessary. 

When the bottom is properly surfaced with coarse sand or gravel it 
does not as a rule require another coat for four or five years. When 
there is a rapid deposit of mud it will, of course, soon become covered 
up, but a location where this takes place with much rapidity should 
perhaps be better left alone, as the seed oysters are liable to suffocation 
by the deposit of material upon them. A strong current will prevent the 
deposit and keep the surface scoured after it has been once prepared. 



OYSTERS AND METHODS OF OYSTER-CULTURE. 301 

SEED. 

After the ground has been thoroughly prepared according to its 
requirements, the next consideration is the actual planting of the 
oysters. Planters follow one of two methods, as their interests and 
experience may dictate; they either plant seed oysters and raise them 
to an adult or marketable size, or they use cultch to catch the spat, 
which may be either sold as seed or retained until it has grown. The 
former method is perhaps the simpler and more uniformly successful in 
most localities, and it will be, therefore, first discussed. 

Seed oysters are young or immature oysters suitable for planting. 
They vary in size from minute "blisters" up to well-grown oysters, 
which will be ready for market in six months after they have been 
bedded. In most cases they run in size between 1 and 1£ inches, or 
from about the size of a silver quarter up to the size of a silver dollar. 

The seed is obtained either from planters who make a specialty of 
raising it, or from the natural reefs, or from various places along shore 
where there may be an abundant set of spat. In certain localities 
gravel beaches often show a strong set in the area between tides, where 
it may be collected at low water, or beyond low- water mark, where it 
may be dredged or tonged from boats. In some parts of Long Island 
Sound there is an extensive fishery for seed oysters in localities such 
as described. 

Some planters collect seed for themselves, but most of them prefer to 
buy from those who make a specialty of that branch of the industry. 
The puice varies in different localities and with the character and size of 
seed, from 10 cents to $1 per bushel. The larger growth of seed brings 
a better price than the smaller, as it takes a shorter time to bring it to 
maturity and it is less susceptible to the attacks of enemies. The care 
with which the seed has been sorted is also a prime factor in the cost. 
Seed, just as it comes from the beds, contains much besides oysters; 
sometimes as much as 75 per cent consisting of old shells, sponge, and 
other rubbish. Though such material may be obtained at a low j>rice, 
it is not generally regarded as economical, as a larger quantity must 
be planted than when good seed is used, the bed is littered with unde- 
sirable rubbish of all kinds, and is liable to become stocked with 
enemies which will cause trouble in the future. The unculled seed is 
liable also to grow into rough oysters, crowded into bunches and of 
undesirable shapes, which bring a smaller price when put upon the 
market. 

When culled stock is selected — that is, seed consisting of separate 
individuals of good shape and uniform size — it is said to generally give 
satisfactory results. It is free from rubbish and enemies, and, being 
vigorous, it is able to at once avail itself of such advantages as the 
beds possess and its growth is correspondingly rapid. The oysters 
being separate from the beginning, when they reach maturity they are 
shapely and in good condition. 



302 EEPORT OF COMMISSIONER OF FISH AND FISHERIES. 

It lias sometimes happened that good results have followed the 
sowing of spat-covered shells purchased from the canneries, but this 
method is precarious unless the shells are used in the process of spat- 
collecting to be explained hereafter. 

The locality whence the seed is derived is also important. Oysters 
taken from a warm region, where food is plenty and growth rapid, to a 
colder region, where food is more scanty, are, it is stated, not always 
successfully acclimated unless the transfer is made when the oyster is 
very young. Some planters say that when southern oysters just about 
to spawn are taken to Long Island Sound, the generative products are 
not discharged and many of them die in the course of the season. The 
seed obtained from southern " plants/' however, is as hardy as that 
obtained from the "natives," from which it can not be distinguished in 
either appearance or growth. The planting of southern seed oysters 
was formerly an important industry in Long Island Sound, but it has 
been almost entirely supplanted by shell culture. Each spring a com- 
paratively small number of Chesapeake oysters are set down, as they 
have been found to fatten earlier in the fall than the native stock. 
There is no complaint of excessive mortality among the "Virginia 
plants," and it is claimed that they spawn freely in summer even if 
bedded in the preceding spring. 

SOWING THE SEED. 

The seed oysters are usually scattered over the beds from boats or 
scows. Care should be exercised to get them as equally distributed as 
possible, as experience has shown this to be advantageous to their 
growth. When thrown into heaps many are prevented from getting a 
proper supply of food, and the crowding may also cause irregularities 
in the shape of the shells, thus reducing their market value. 

In order to secure a proper distribution over a bed, it may be roughly 
marked out into areas, say 50 feet square, in each of which an equal 
amount of seed should be planted, by scattering it broadcast with 
shovels or scoops from the boat or scow. In subdividing the bed a few 
rough stakes or buoys may be used as temporary guides. 

Another method is to anchor the boat upon the bed, distribute the 
required amount of seed over the area which can be reached by throw- 
ing the oysters from a shovel, and then move on to the next station, 
where the boat is again anchored and the operation repeated. When 
the scow is emptied a buoy or stake maybe used to mark the position of 
the last deposit, and operations can be resumed from that point with 
the next boat load. By such means the seed is rapidly and evenly 
spread over the bottom. 

In planting on extensive beds where steam power is used the seed is 
distributed from scows, which are slowly towed back and forth, while a 
gang of 8 or 10 men shovel the oysters overboard as rapidly as possible. 
That is the most rapid and economical method, and is the one usually 
employed on the deep-water grounds of Long Island Sound, 



OYSTERS AND METHODS OF OYSTER-CULTURE. 303 

It is riot well to deposit the oysters very thickly. About 300 to 600 
bushels per acre appears to be the usual amount in most places. The 
ground will, of course, support a larger number of yearling seed, but as 
they grow larger there will be more or less crowding and the demand 
for food will be greater. 

In certain places where oyster-planting has greatly increased within 
recent years it is found that the oyster neither grows as rapidly nor fat- 
tens as readily as formerly, and it is supposed by many that the quantity 
of oysters has outgrown the ability of the region to supply them with food. 
The matter has not yet been investigated and the factsin the case are 
not definitely known, but the theory proposed is a plausible one to 
account for the difficulty with which the planter is beset in fitting his 
stock for market. It is well known that when the seed is sowed too 
closely upon a given bed the oysters grow and fatten more slowly than 
upon less thickly populated ground, and only in waters exceptionally 
rich in food can the quantity of seed planted exceed with safety the 
number of bushels stated. When the seed is sowed too thickly there 
is also a tendency to distortion from crowding. 

WORKING THE BEDS. 

When seed oysters of good quality are used it is generally not 
regarded as necessary to "work the beds," although care should be 
taken to prevent, if possible, the inroads of enemies. The various 
methods of attempted protection from enemies have been discussed in 
another connection. 

It is sometimes advantageous to dredge over the planted beds to 
remove debris, seaweed, etc., which has drifted upon them, and which 
of itself and by the collection of sand, etc., would smother the oysters 
if allowed to remain. If the bottom is not perfectly fixed it may be 
necessary to shift the oysters during their growth in order to prevent 
"■sanding," i. e., being covered with sand, etc., from the drifting bottom. 

While oysters grow most rapidly upon or near muddy bottom, they 
are often in some respects objectionable if placed upon the market 
directly from such beds. Some planters, therefore, transplant them to 
hard bottom for several months before sending them to market, it being 
said that this improves their flavor and appearance by causing the 
umddy matter in the gills and mantle cavity, as well as in the intestine, 
to be gradually cleared out and disgorged. 

In parts of Long Island Sound many of the planters take up a por- 
tion of their stock in spring and transplant it to such ground as may 
be available in the bays and harbors. Such transplanted oysters fatten 
and grow more rapidly than those left in the deeper water; the differ- 
ence in condition is manifest to even the inexperienced, and a higher 
price is obtained and a more ready market found for the "harbor 
plants." The area available for this purpose, however, is insufficient to 
permit of the transplanting of more than a very small proportion of 
the "Sound stock." 



304 REPORT OF COI MISSIONER OF FISH AND FISHERIES. 

The bottom from which the oysters have been shifted is, of course, 
cleansed of rubbish when the oysters are taken up and may be at once 
utilized for fresh seed. Some oystermen prefer to let it lie idle for a 
year, supposing that this increases its fitness for a further crop, but 
there appears to be no good reason for this, though it may be that this 
course permits of a recuperation of the food supply on the fallow beds. 

The length of time during which the plants are allowed to lie depends 
upon the location of the beds, as affecting the rapidity of growth, upon 
the size of the seed planted, and upon the judgment of the planter. In 
many places "yearling" seed will be ready for the market in two or 
three years after being planted, i. e., when the oysters are 3 or 4 years 
old, but in exceptionally favorable localities, such as Jamaica Bay, 
Long Island, such seed is said to grow to marketable size in six months 
or a year. In some places it is said to now take a year longer for the 
oysters to mature than when planting was first practiced. 

As large oysters bring a better price than small ones, it generally 
pays to allow them to grow for a year or two after they reach a market- 
able size, but this is a matter which the planter will determine for 
himself, as conditions vary with the locality. 

As the planter generally wishes to harvest a portion of his crop each 
year, it is customary to divide the beds into sections, which are planted 
in successive years in such a manner as may suit the plan of operations 
of the particular grower concerned. 

PLANTING WITH CULTCH OR STOOL. 
PRELIMINARY CONSIDERATIONS. 

This method of oyster-culture is that which was first adopted, and to 
it and its inodificatiQns we must doubtless look for future growth in 
the oyster industry. The method of planting seed oysters improves 
the size, shape, and flavor of the plants, and to some extent increases 
the quantity of oysters available for the markets, but, nevertheless, 
many of those which are raised from seed derived from the natural 
beds would have reached a marketable size if left to remain. Moreover, 
the natural beds are now being depleted at a rapid rate by the drain 
which has been made upon them. Not only are they compelled to 
supply oysters for market, but the young growth is now carried off to 
be planted elsewhere. As the number of spawning oysters on the beds 
is reduced and as the spawners become more scattered, the reproduc- 
tive capacity of the beds is being lowered, and at the same time the 
removal of both oysters and shells leaves fewer points of attach oient 
for the young spat. As the seed-producing power of the natural beds 
becomes reduced from these various causes, the planter must have 
recourse to other methods for obtaining his set of young oysters. 
Fortunately, there is a well-tried method which may be adopted. The 
oystermen long ago noticed that under certain conditions not only did 
natural objects of various kinds become covered with young oysters, 



OYSTERS AND METHODS OF OYSTER-CULTURE. 305 

but other objects accidentally dropped overboard would often, when 
recovered a few weeks later, show a heavy set of spat. Naturally they 
began to throw objects into the water for the express purpose of 
collecting the spat and thus increasing the amount of seed available 
and from this beginning the present system of spat-collecting now in 
use in our waters was developed. 

For this method of planting it is, of course, essential that there 
should be in the vicinity of the beds spawning oysters, either of volun- 
teer growth or planted, and that the temperature of the water should 
be between 68° and 80° F. during a period of some weeks' duration. 

PREPARING BOTTOM. 

The bottom used for this method of cultivation should be firmer than 
that which will suffice for bedding well-grown seed, though soft bottom 
may be prepared so as to be satisfactorily used. If the bottom is very 
soft it may be overlaid with gravel or sand in the manner before 
described (p. 300), and upon this the collectors or cultch may be depos- 
ited. In a moderately soft bottom the cultch can be applied without 
previous preparation other than to clear the ground of all debris which 
would interfere with working it. Hard, gravelly bottom in shoal water, 
which may be of little use for the raising of adult oysters on account 
of the absence of food, may prove an excellent place for "the collection 
of spat, and the same may be said of some places with a stiff clay soil. 

One of the great difficulties in spat-collecting is to avoid the deposit 
of sediment upon the cultch, as an amount of sedimentation which 
would have no effect whatever upon the adult oyster would prove 
absolutely fatal to the young spat. At the time of attachment the 
infant oyster is about one-ninetieth of an inch in diameter, and the 
deposit of a very slight film either before or immediately after the 
falling of the spat would be sufficient to cause its suffocation. It will 
be seen, therefore, that a soft bottom upon which the large oysters will 
thrive, or an amount of sedimentation which may favor the rapid growth 
of the adults from the food matter whifch it contains, will effectually 
prevent, in many instances, the cultivation of spat. 

CULTCH, COLLECTORS, STOOL. 

By these terms is understood any firm and clean body placed in the 
water for the purpose of affording attachment to the spat or young 
oyster. A great variety of objects have been suggested and used for 
this purpose, both here and abroad, and some of these will be now 
discussed. 

Oyster shells. — In this country oyster shells are the oldest and most 
generally used form of cultch. Tbey are usually merely spread upon 
the bottom, being thrown broadcast from boats in the manner which 
is described for planting seed oysters (p. 302). When the bottom is 
sufficiently hard to prevent the submergence of the shells, it is custom- 
ary to spread them as uniformly as possible over the ground, so as to 

P. C. E. 1897 20 



306 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 

offer the largest available area for the attachment of the spat. Where 
the bottom is so soft, however, that the shells would tend 'to sink before 
the young oysters have reached a size to enable them to successfully 
combat such "conditions, it is preferable to surface the bottom in the 
manner described for planting seed oysters, or the shells may be thrown 
over so as to fall in flat heaps, those at the base forming a foundation 
support for those above, leaving only the upper shells available for the 
set of spat, those below soon becoming buried in the mud. 

Shells may be planted in all depths of water with equal facility. 
They are cheap and readily obtainable in all oyster regions. Clam and 
scallop shells are also used in the same manner. The quantity required 
to properly "shell "a bed depends upon the nature of the bottom. 
When the ground is soft a larger number is necessary than upon hard 
ground, because in the former case many become buried in the mud or 
covered up by the others, whereas in the latter instance they all become 
available as collectors. 

Upon soft ground some planters, instead of preparing the bottom 
wifh sand or gravel, apply a layer of oyster shells a, couple of months 
before it is time to distribute the cultch* proper. Those first applied 
sink a short distance into the mud where they become suspended so as to 
form a more or less solid substratum which supports the cultch applied 
later. A bed so prepared simulates the natural banks, which in most 
places overlie a mud bed that, in its upper portions, has acquired some 
consistency and firmness by the shells lying buried in it. 

After a muddy bed has been shelled for a number of successive years 
it will be found to become gradually firmer. Each year some of the 
planted shells become covered up and are left remaining when the 
oysters are removed and thus it happens that the bottom of a well- 
handled planting- ground improves with use. 

When the oyster or clam shells are thrown from the boats they will 
be found to fall so that the convex side rests upon the bottom. There 
is nothing very remarkable or inexplicable in this, as it is entirely in 
accordance with the ordinary laws of the resistance of fluids to the pas- 
sage of a solid body through them; but in sowing the shells, however, 
it is important that they so fall. In most cases, if such cultch be 
examined, it will be found that nearly or quite the entire set of spat is 
upon the convex or lower side. As the shell falls its greatest convexity 
rests upon the bottom, its edge being held clear of the mud in the form 
of a projecting ledge, sheltered on its under side from the suffocating 
sediment deposited upon the upper surface. In ordinary situations 
perfectly flat pieces of tile, shale, etc., would be vastly inferior to shells, 
for the lower surface would lie close to the bottom while the upper 
would become covered with a muddy deposit from the water, between 
the two the young oyster having but scant opportunity tor fixation. 

It has been observed that when shells and gravel are spread upon 
the same beds the former usually catch the larger amount of spat, 
especially in years in which there is but a moderate set. The planters 



OYSTERS AND METHODS OF OYSTER-CULTURE. 307 

and oystermen attribute this to the fact that the shells project a greater 
distance above the bottom and that therefore the fry come into contact 
with them first in their descent for attachment, but as the set is mainly 
upon the convex side of the shell and therefore underneath, it will be 
seen that the true explanation of the superiority of the shells is that 
given above. 

The quantity of shells sowed upon any given bottem will depend upon 
the judgment of the planter, the general rule being to sow more on soft 
than upon hard bottom, for the reasons before stated. The usual quan- 
tity appears to be from 250 to 500 bushels of shells per acre, most of the 
planters using about 400 bushels per acre, except upon very muddy 
bottom ; but in Long Island Sound there is an increasing tendency to 
use greater quantities. 

In some places the shells may be obtained for the cost of transporta- 
tion. This was the general rule years ago, but with the increase in 
planting a charge of from 2 to 5 cents x>er bushel is now made for them. 
Many planters who operate canneries or ship "shucked" oysters have 
ready at hand an abundant supply of shells for use as cultch. The cost 
of spreading ranges from £ to 2 or 3 cents per bushel, according to the 
location of the beds and the cost of labor, etc. 

The principal objection to the use of oyster shells is that they are of 
such large size that many more spat attach themselves than have room 
to grow and, at the same time, they are so strong and massive. that itvis 
difficult to break them in pieces so as to allow for the expansion of the 
young. As a consequence many young oysters which have successfully 
passed through the early stages of their fixed conditions are smothered 
or overgrown by their more vigorous fellows, which are themselves dis- 
torted by the crowding to which they are subjected. Many are thus 
wasted which would, under better conditions of attachment, have grown 
to a marketable size. (Plate ix.) 

For the reasons mentioned scallop, "jingle," and other fragile and 
friable shells (plate xvin, figs. 1 to 6) are, when they can be obtained in 
quantities, to be preferred. Such shells will break up under the mutual 
pressure exerted by the oysters during their growth and the latter will 
then be liberated from the bunches and will tend to grow into shapely and 
desirable forms, with a smaller rate of mortality. When the currents or 
waves are very strong such frail shells as jingles may prove too slight 
to withstand their action and the planter using them may find, to his 
surprise, that much of his cultch has been carried away. Upon some 
portions of the Pacific coast it is said that the wave action and the 
currents are so strong that the light, thin shells ol the native oyster are 
swept away or thrown upon the shore. Otherwise, and for the reasons 
before stated, these shells appear to be well adapted to the process of 
sowing and they can also be obtained cheaply and in large quantities. 

Other methods of using shells. — It has been recommended or suggested 
that shells of various kinds could be strung upon wires, etc., and sus- 
pended in festoons from stakes planted in the bottom. This would, of 



308 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 

course, prevent their submergence in places where the mud was very 
soft, but as each shell would have to be separately handled it will be 
found that this method is too expensive to be warranted by the present 
condition of the oyster business. Another method of utilizing oyster 
shells as cultch is treated of in connection with the subject of pond 
culture (pp. 322-330). 

Gravel and pebbles. — This is a form of cultch which is much favored 
by the planters in some parts of Long Island Sound, its principal 
advantages being the small size of its constituent particles and its 
cleanliness. As a rule the pebbles are so small that but few spat fix 
themselves to each (plate xviii, fig. 7) and, consequently, there is little or 
no danger of crowding. Not only do a larger proportion of the young 
oysters survive their infancy, but they develop into deeper, more regular 
shapes, are free from bunches, and, consequently, bring a higher price in 
the markets. Where the*trade in " shell stock " is large the shape of the 
oysters is a consideration of importance, but where only shucked oys- 
ters are shipped irregularities in shape are less undesirable. The gravel 
is more* cleanly than shells, because it is not attacked by the boring 
sponge, which gives rise to much of the debris found upon the oyster- 
beds. There is also less liability to the introduction of oyster enemies 
than when shells are utilized. 

The bottom used for obtaining a "pebble set" must be firmer than 
that which will suffice for the sowing of shells, the gravel being heavier 
in proportion to its surface and therefore more liable to sink. It also 
presents less surface on muddy bottoms, where the pebbles will soon 
become buried to their equators, and if there is any sedimentation there 
is left no surface available for the attachment.of the fry. Bounded, 
water- worn pebbles are usually preferred, such offering more surface 
free from sediment than flat stones. They afford, perhaps, the best form 
of cultch for use upon firm bottoms, when there is sufficient current to 
prevent the rapid deposit of sediment. It is observed that gravel 
beaches, when these conditions, obtain, are often the most valuable of 
natural spattmg-grounds. In some places gravelly material dredged 
from harbors and channels during the improvement of waterways is 
used to advantage. Crushed stone, averaging about the size of a wal- 
nut, is also an excellent collector. Gravel or crushed stone is generally 
more expensive than shells, costing from 5 to 7 cents per bushel. The 
custom is to sow from 25 to 30 cubic yards (from 500 -to 600 bushels) per 
acre when used alone, but a smaller quantity if shells are also used. 

Scrap tin, tin cans, etc. — In some places old tin cans and scrap tin of 
various kinds is found to give good results when used as cultch. It 
has the advantage of becoming corroded and gradually dissolving in 
the salt water, thus releasing the young oysters before they begin to 
crowd one another and allowing them to grow into well- shaped adults. 
Moreover, as the cultch each year disappears in solution, there is no 
debris from this source to litter the ground and to cause the expense 
of culling. It seems that, in the form of old tin cans, this type of cultch 



OYSTERS AND METHODS OF OYSTER-CULTURE. 309 

might have some advantage on muddy bottom where there is a rather 
rapid sedimentation. Such cultch is light in proportion to the surface 
presented, it would not readily sink, and the upper half of the interior, 
and to some extent the lower half of the exterior would present sur- 
faces protected from sedimentation upon which the young oyster could 
lodge itself. By the time the can disintegrated the oysters would no 
doubt be sufficiently grown to withstand the action of the mud. The 
tin is distributed over the bottom as in the case of shells and gravel. 

Brush for soft bottom. — Where the bottom is so soft that ordinary 
methods can not be used, it will sometimes be found that fagots and 
brush make most efficient collectors. The brush is thrust firmly down 
into the mud in such a manner that the small branches are at some 
distance above the bottom. They will offer a large surface to the 
water, a slight current will tend to keep them free from destructive 
deposits of sediment, and in water well charged with the swimming fry 
will almost certainly yield a full set of spat. The brush is lifted at the 
proper time by means of a crane or boom and windlass. This method 
was used with some success at the town of Groton, Conn. The seed 
was left to grow to a marketable size on the brush, but owing to the 
liability of the large oyster to drop off into the soft mud below, it was 
sold as soon as possible. 

Brush, straw, etc., may also be used by collecting the material into 
bundles, sheaves, or fagots, which may be anchored by stones or sus- 
pended from stakes. As it is usually unnecessary to resort to such very 
soft bottom, it will be found in most cases that shells, gravel, or scrap 
tin will be more serviceable and satisfactory. Brush collectors would 
be difficult to use in regions of violent wave action. 

Other collectors. — Many materials have been suggested as suitable for 
collectors, but the foregoing appear to be the only ones which have 
proven practical on a large scale in our waters. Tiles and roofing slates 
arranged in various forms have been found satisfactory by European 
culturists, but are apparently not adapted to use here where labor is 
high and oysters are cheap. These collectors will be discussed in 
another connection. Pieces of bricks, broken pottery, and similar 
materials may suggest themselves to the planter as local substitutes 
for shells and gravel. Hard-wood chips and bark might prove useful, 
but are hardly to be recommended. 

COATING- CULTCH. 

To overcome the difficulty, which has been mentioned, of the set upon 
collectors being so dense as to interfere with its subsequent growth, it 
has been proposed to coat the cultch with some material which will 
flake off, either under the mutual pressure exerted between the grow- 
ing oysters, or when it is scraped with a suitable instrument. This 
device was apparently first used in France, where it was adopted to 
avoid the theretofore necessary breakage of the tile collectors. The 
coating is detached from the tiles with a chisel- shaped instrument, 
somewhat resembling a putty knife. 



310 REPORT OF COMMISSIONER OF FISH AND FISHERIES 

Apparently this method has never been used in our waters, but where 
it is necessary to use oyster shells for cultch it might perhaps be 
applied to advantage. In this case the fry could not be economically 
detached by hand, but there is little doubt that the growing oysters 
would automatically liberate themselves. The coating used in France 
consists of a mixture of sea water, lime, and sand, or hydraulic cement, 
"stirred to the consistency of thick cream." Various formulae are used 
by different culturists, three of them being as follows: 

1. One part quicklime, 3 parts fine sand. 

2. One part quicklime, 1 part fine gray mud. 

3. First a light coating of quicklime, and, after drying, a coat of 
hydraulic cement. 

The coating should be such as not to readily wash off, yet sufficiently 
brittle to flake under the mutual pressure exerted between the growing 
oysters, and about ^-inch in thickness. 

For convenience in coating, Dr. Eyder recommended that the shells 
be jdaced in a wire basket and dipped into the cement vat, the mixture 
being then allowed to set before the shells are used. 

GENERAL CONSIDERATIONS ON SPAT- COLLECTING. 

Whatever may be the character of the cultch, it should invariably 
be clean and without any surface deposits which might tend to prevent 
the fixation of the spat. For the same reason the cultch should not 
be placed upon the beds long before the season for setting. 

In almost any body of water, except where the currents are swift, 
there is more or less sedimentation, and it is obvious that the shorter 
the time that a body is exposed to such action the thinner must be the 
deposit. If the cultch is placed in the water long before it is needed 
the deposit of sediment is often so thick as to stifle the young oyster, 
but on the other hand if the time be well chosen a practically clean 
surface is presented and a good set is more likely to reward the planter. 
The latter's aim should, therefore, be to determine as nearly as possible 
the time when the maximum amount of spawn falls, and to so regulate 
his operations that his cultch is laid down but a few days before. The 
time will vary somewhat with the locality, and if there is no local expe- 
rience to guide the beginner he may be compelled to experiment a little 
to find the most favorable time for exposing his collectors. It should 
be remembered that while the spawning season in any given locality 
extends over a number of months, the majority of the oysters spawn 
within a more circumscribed period, usually about midway between the 
two extremes. 

If the time at which the collectors are exposed be well chosen, and 
the location of the beds properly selected, the planter may or may not 
obtain a good set. Sometimes one bed will show a strong set, while its 
neighbor appears to have been entirely passed over by the fry. Often 
the cultch in one part of the bed is thickly incrnsted with spat, while 
another portion, apparently equally well located and upon which an 



OYSTERS AND METHODS OF OYSTER-CULTURE. 311 

equal amount of care has beeu expended, will prove utterly sterile. 
While iu many such cases the causes are not known, yet the experience 
of planting has thrown some light upon the matter. It is known that 
cultch can not be thrown down at random with any strong expectation 
of success. The water is not everywhere charged with the swimming 
fry, and the experience of planters has shown that they are often dis- 
tributed in streaks or belts, which appear, to some extent, at least, to 
be conditioned by the currents. If cultch be placed in a current it will, 
other things being equal, be more likely to catch a set than when in 
still water. Even a strong current does not appear to interfere with 
the fixation of the young, and as it brings a greater body of water into 
contact with the collecting surface, some of it is more likely to contain 
fry at the stage for fixation. 

It is also obvious that the water is not likely to contain many fry 
unless there are spawning oysters in the vicinity, and it is, therefore, 
the part of wisdom to locate the collectors in the vicinity of natural 
or artificial beds containing mature oysters. Even where the oysters 
are so scattered as to hardly pay for working, it will be usually found 
that there is sufficient spawn fertilized to provide considerable seed if 
it be given proper facilities for attachment. For reasons readily seen, 
it will be advantageous to locate the collectors so that the predominating 
current sweeps from the spawning oysters toward the collectors. In 
some localities it will be found that the entire set occurs in the tidal 
zone; that is, in the area between low and high water. The reason for 
this is not yet fully understood, but if it should prove to be because the 
embryo oyster is lighter than the dense sea water, and therefore can 
not sink to the bottom, or because the sedimentation is too rapid 
below low-water mark, or almost any other reason except the softness 
of the bottom, then the cultch must be confined to the area between 
tides if it is to be effectual as a collector of spat. The most careful and 
uniformly successful oyster-culturists do not depend entirely upon the 
spawn derived from neighboring beds, but usually distribute over the 
spatting- beds a number of mature spawning oysters in the proportion 
of 30 to 60 bushels per acre, these being usually put down before the 
cultch, so that the oysters will become *° «ome extent acclimated before 
the spawning season. 

As the cultivated area increases it becomes unnecessary to use so 
many brood oysters, and in some places where they were formerly used 
reliance is now placed solely upon the floating fry* derived from the 
mature oysters on neighboring beds. Upon theoretical grounds it would 
appear to be preferable not to scatter these " mother oysters" too widely. 
There would seem to be greater certainty of fertilization when the 
oysters are grouped, and there are ample time and superior facilities 
for securing distribution over the beds in the embryonic condition. 
The embryo exists for a period as a free-swimming form, and during 
that time it may be carried considerable distances by its own exertions 



312 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 

and by the action of the currents. On the other hand, the eggs, and 
especially the spermatozoa, will probably die unless they fulfill their 
destiny within a much shorter period, and the sooner they are brought 
into contact with one another the better, and the smaller the bulk of 
water through which they are at first distributed the larger the number 
which will accomplish successful union. 

Upon these considerations is based the advice not to scatter the 
"mother oysters" too widely. Fifty bushels of oysters, 250 to the 
bushel, scattered evenly over an acre would allow one oyster in every 
22£ linear inches in each direction, plenty near enough if they were to 
all spawn at one time, but it must be remembered that the proportion 
ripe at any one time is not so large, and there is a possibility of all of 
the oysters over a considerable space being of one sex. 

The "mother oysters" used for this purpose are preferably obtained 
from the neighborhood of the planting-ground. It has been remarked 
in another connection that transplanting mature oysters, especially 
from a warmer to a colder region, may have the effect of checking the 
development of the genital products, and Dr. Eyder has commented 
upon the fact that the spermatozoa of ripe oysters are killed by being 
changed to much denser or warmer water than that in which they have 
been living. The endeavor should be, therefore, to study the con- 
ditions on the planting-grounds, and to procure the spawners from 
beds as nearly as possible similar in the conditions of temperature and 
density. Where this consideration can not be closely followed, as for 
instance in the shipment of eastern oysters to places on the Pacific 
Coast, the brood oysters should be sent during the fall preceding the 
season at which the cultch is to be put down„ They will then be pretty 
well disgorged of their ripe genital products and the time intervening 
before the next period of sexual activity will probably be sufficient to 
acclimatize them. 

WORKING THE BEDS. 

Many planters are content to allow their beds to remain unworked 
until they are ready to market their crop, whether this be one, two, 
three, or more years. In some instances this may be satisfactory, but 
often, and perhaps usually, it is better to go over the beds with tongs or 
dredges, cleaning up the debris and separating the oyster clusters or 
even in some cases removing the seed to localities in which the condi- 
tions are more favorable for rapid growth, for in many cases the best 
spatting-grounds are not the most favorable for subsequent growth. 

The stage at which the planter will find it most profitable to sell his 
oysters will depend much upon circumstances. Sometimes the set of 
spat will be greater than could be advantageously grown upon the area 
covered and some of it could be manifestly removed to advantage. 
Some planters find it more profitable to sell their oysters as seed, thus 
receiving quicker returns for their investment and also lessening the 
possibility of losses due to the appearance of enemies or the advent of 



OYSTERS AND METHODS OF OYSTER-CULTURE. 313 

untoward conditions. In many cases it will pay the planters to spe- 
cialize, some raising seed for sale to others who devote their capital and 
enterprise to the work of raising the oysters to a marketable size. 

Even if the oysters are to be left upon the spatting-bed, it is often 
better to work over the ground during the first year, removing the 
debris and breaking up the clusters of young oysters, so as to insure a 
greater survival and superior shape. As has been already mentioned 
in treating of the planting of seed, it is often advisable to shift the 
oysters to other ground during the last few months before marketing 
in order to fatten them, improve the flavor, and cause the gradual dis- 
gorgement of mud from the intestine and mantle chamber. 

A keen watch should be kept at all times to detect the presence of 
enemies, some of which may be with more or less success combated by 
the methods mentioned on pp. 313-319. The spattiug-beds are espe- 
cially subject to the attacks of various enemies which find in the vast 
numbers of thin-shelled young an abundant and readily obtained food 
supply. The starfish, especially, at times appear in vast schools or 
swarms, and often a bed is almost completely destroyed before the 
planter is aware of what is taking place. 

PROTECTION FROM ENEMIES. 

In the case of most of the enemies of the oyster it is impossible to 
indicate efficient means of protecting the beds from their inroads. The 
impossibility of knowing at all times the exact conditions prevailing 
upon the bottom, the suddenness with which many of the enemies 
appear upon the beds, and the insidious character of their attacks all 
add to the difficulty which the planter finds in preventing the destruc- 
tion of his property. 

PROTECTION FROM FISH. 

It is possible to protect oysters in shallow water from the attacks of 
fishes by surrounding the beds with palisades of stakes driven into the 
bottom at sufficiently close intervals to prevent the passage of fish 
between. Upon the Atlantic coast the inroads of fish are not suffi- 
ciently formidable to require such protection, although the drumfish 
causes some loss to planters in the vicinity of New York. Upon the 
Pacific coast, however, and especially in San Francisco Bay, stockades 
are necessary to prevent the absolute destruction of the planted beds 
by the stingray, the stakes being driven at intervals of about 4 inches. 
It is necessary to keep the inclosure in good repair, as a school of rays 
entering through a small breach may utterly ruin the bed. 

PROTECTION FROM STARFISH. 

Many methods, have been suggested for combating this destructive 
enemy of the oyster, most of them being of no practical utility. Bar- 
riers are utterly useless, for the very small starfish are among the most 
destructive and the largest ones are able to pass through an orifice of 



314 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 

such small dimensions that it is impracticable, for manifest reasons, to 
build a barrier so close in structure as to exclude them. Some attempt 
has been made to catch them in traps, made of laths and baited with 
fish, crab meat, clams, etc. These traps are constructed and tended 
like lobster pots, and while it has been found that the starfish can be 
taken through their agency, the method is too laborious and inefficient 
to be used for the protection of extensive beds. Various devices for 
catching starfish have been patented from time to time, but none of 
them appear to have been of practical value. 

Upon the theory that the starfish prefers the mussel to the oyster as 
food, it has been proposed to surround the oyster-beds with a growth 
of mussels with the expectation that the starfish will not pass over the 
mussel bed to obtain the less desired oysters. Investigations in Long 
Island Sound show that this expectation is not realized in practice, 
and, moreover, in favorable locations, the growth of mussels is so rank 
that they themselves become a menace to the planter by overgrowing 
his beds and suffocating the oysters. This method of protection is also 
wrong in principle, for by supplying the starfish with additional food 
we better its conditions and thereby aid in increasing its numbers. 

For catching starfish some planters use the ordinary oyster-dredge, 
an implement which has some advantages when it is desired to cull the 
stock, but, in general, it involves unnecessary labor and also crushes 
and kills many young oysters. A lighter dredge of similar construction 
is also used, and on the shallow beds tongs may be sometimes employed 
to advantage. 

The oyster-growers of Long Island Sound, who have had more expe- 
rience in fighting starfish than those of any other section, find that 
eternal vigilance is the price which they must pay for even the compara- 
tive safety of their beds. The beds are closely watched and worked 
over with dredges and tangles. Tugs are kept more or less constantly 
at work, and all starfishes taken, either in the ordinary work of oyster 
dredging or during "starring," are carefully destroyed. Thousands of 
bushels are caught during the year and much money is expended in 
the work, the result being that many beds, through timely and unceas- 
ing attention, are saved from utter destruction. The tangles or mops 
employed are an adaptation of a device long used by naturalists for 
collecting spiny forms from the sea bottom, and their use in fighting 
the starfish was first suggested by the United States Fish Commission. 
They consist essentially of an iron bar to which small chains or wires 
are attached at intervals of about a foot, mops or bundles of rope yarn, 
cotton waste, or similar material being distributed at short distances 
along the chains. The bar is fastened to the ordinary dredge line or 
chain and is dragged over the bottom, being hauled in at frequent 
intervals for the removal of the starfish which have become entangled. 
Most of the tangles used in Long Island Sound have frames weighing 
from 100 to 150 pounds, and to prevent this heavy mass of metal from 
crushing small and thin-shelled oysters they are provided with a hoop, 



OYSTERS AND METHODS OF OYSTER-CULTURE. 



315 



12 or 14 inches in diameter, at or near each end of the bar. These 
hoops ride over the bottom like runners and the crushing surface is 
thus much reduced. The general construction of these tangles is shown 
in cut 2. The weight appears to be unnecessarily great, all that is 
actually required being that which is sufficient to hold the tangles 
upon the bottom when in motion, a condition which is largely insured 
by the sagging of the chain used in towing. 

A vessel-owner at New Haven, Capt. Thomas Thomas, who has been 
very successful in "starring," uses a much lighter tangle constructed 
as follows: To a half-inch chain, about 8 feet long, stout wires 12 




Cut 2.— Tangle. 



Cut 3.— Tackle. 



or 14 feet long are attached at regular intervals, and to these wires 
are fastened mops or swabs of cotton waste. The chain is securely 
lashed to a bar about 7 feet long by 1£ inches wide and half an inch 
thick, provided with a bracket and eye for the attachment of the drag 
chain, as shown in cut 2. 

When in use this tangle covers an area about 7 feet wide and 12 feet 
long, forming a dense mat of snarled cotton threads. One of these is 
towed on each side of the vessel, like a dredge, and, sweeping over the 
bottom, entangles the starfish with which it comes into contact. The 
length of time during which the mops are towed depends upon the 



316 REPORT OF COMMISSIONER OP FISH AND FISHERIES. 

abundance of the stars, being greater when they are few than when 
they are plenty. The starfish are killed by being momentarily immersed 
in a tank of boiling water, the bath being heated by a steam tap con- 
nected with the boiler. The tanks are about 7 feet long by about 18 
inches wide and deep, and are located one on each side of the main 
deck, just inboard of the roller over which the tangle chain runs. To 
facilitate the immersion and handling of the tangles, a davit, with block 
and fall, is rigged on the hurricane deck over the tank, as shown in 
cut 3. A lanyard is rove through an eye welded to the back of the 
hook on the fall and the other end is fastened to the davit, its length 
being so adjusted that the hook is automatically tripped by the weight 
of the tangle when the hauling part of the tackle is eased and the mops 
lowered to near the surface of the water. 




Cut 4.— Drill-dredge in position for work. 



Some of the oystermen pick the starfish out by hand, but this is a 
slow and laborious process and, moreover, it is almost an impossibility 
to so remove all of the small ones. By using the arrangement just de- 
scribed the labor is lightened and the killing of the stars assured. By 
using a tangle on each side of the vessel one is always at work while the 
other is being hoisted. It is stated that upward of 100,000 starfish 
have been caught in a single day by a boat using the apparatus described. 
It is usual to work on the beds until not over half a bushel of starfish 
can be caught in a day, the beds then being considered safe, although 
at any time a host may arrive from a neighboring bed. 

United effort on the part of the planters is necessary for success in 
fighting starfish. A neglected bed is, in a measure, a menace to others 
in the vicinity: for if starfish are left to multiply without hindrance 
they will move to neighboring beds as soon as they have exhausted 
the supply of food upon the first. 



OYSTERS AND METHODS OF OYSTER-CULTURE. 



317 



PROTECTION FROM DRILLS. 

No method of proved efficiency has yet been devised for protecting 
oyster-beds from the inroads of the drill, but by systematic attention 
something could, no doubt, be done to lessen its destructive effects. 
In culling the oysters brought up in the dredge or tongs care should 
be exercised to destroy the drills. Most of them, however, will pass 
through the intervals of the ordinary oyster- dredge, and to obviate this 
a finer bag might be used within the dredge. This could be used 
especially in cleaning up the beds preparatory to planting. It should 
be remembered, in this connection, that it is possible to infect new 
grounds with the drill by its transportation thereto with the seed. The 
deep-water beds of Long Island Sound have of recent years suffered 
more and more from this pest, and it is supposed that this is accounted 




Cut 5. — Drill-dredge open for emptying. 

for by the use of seed from the drill-infested beds in the less saline 
inshore waters. The use of tangles for catching starfish also, no doubt, 
aids in the distribution of the drills by dragging them from place 
to place. 

The most promising method which has yet been proposed for catch- 
ing this enemy is the invention of Oapt. Thomas Thomas, of New Haven, 
Conn., who has applied for letters patent thereon. It consists of a rec- 
tangular frame of iron bars about 4 feet long, 2 feet wide, and 18 or 20 
inches deep. The bottom, ends, and rear are covered with an iron wire 
screen, having a mesh of about half an inch, the top and front being 
left open. To the upper rear edge of the frame is hinged a stout 
wire screen of about 1-inch mesh, its length being such that it may 
fall between the ends and its breadth being equal to the diagonal 
of the end pieces when in place ; therefore it extends from the lower 



318 REPORT OP COMMISSIONER OP FISH AND FISHERIES. 

front edge to the upper rear edge of the frame. Attached to the 
lower front bar is a broad blade of iron or steel, inclined somewhat 
downward and forward from the plane of the bottom of the box. The 
whole is attached to a dredge frame, to which the chain used in 
dragging is made fast. (See cuts 4 and 5.) 

When this appliance is dragged over the bottom the oysters and other 
inhabitants of the beds, together with shells and debris of all kinds, 
are lifted from their resting-places by the blade and deposited upon the 
inclined screen or apron. The motion of the trap and the pressure 
exerted by the accumulating material in front gradually pass the mass 
backward across the screen, the smaller particles, drills, etc., sifting 
into the box, while the oysters, being too large to pass through, finally 
fall over the edge behind. 

By this means the varied material on the beds undergoes a process 
of screening, the oysters being automatically returned to the bottom, 
while a large part of the debris is held and brought to the surface. 
That the device will accomplish this has been demonstrated, but whether 
the drill can be successfully fought by this means has still to be shown, 
although the prospects are favorable. 

PROTECTION PROM WINKLES. 

The conchs or winkles have never been a serious menace to our 
oyster-beds. Their small numbers and large size and the large size of 
their egg cases make it possible to successfully fight them by destroy- 
ing all winkles and egg cases brought up in the process of dredging or 
tonging. 

PROTECTION PROM SPONGES, HYDROIDS, MUSSELS, ETC. 

The growth of sponges, hydroids, etc., when so rank as to threaten 
the welfare of the oysters, may be kept down by working over the beds 
with the oyster dredge and culling out the debris. A thorough cleaning 
up of the ground before planting and the use of clean seed and cultch 
go far toward the prevention of trouble from this source. 

PROTECTION PROM STRONG VEGETABLE GROWTHS. 

In places where eelgrass (Zostera), etc., grow so rapidly as to cause 
stagnation of the water and suffocation of the oysters some means must 
be adopted for its removal. Sometimes it may be removed with an ordi- 
nary scythe at low water. A grower in New Jersey has invented for 
this purpose what has been termed an "aquatic mowing machine." 

It is described as follows : 

Eelgrass grows abundantly in some parts of the Navesink River and, as in other 
localities where it is found, acquires in due time full possession of the areas where 
it grows, rendering them useless for oyster-culture. In combating this enemy of 
the oyster-planting industry, Mr. Charles T. Allen, of the firm of Snyder & Allen, 
Oceanic, N. J., has achieved a degree of success heretofore unequaled. After 
expending much fruitless labor in efforts to mow the eelgrass with a scythe, a method 
which proved impracticable because the water was sometimes too deep and also on 



OYSTERS AND METHODS OF OYSTER-CULTURE. 319 

account of the difficulty of cutting grass growing under water, he invented in 1885 
and has since used a device which may be termed an aquatic mowing machine. 
The machine is rigged on a square-ended scow 20 feet long by 8 feet wide. On the 
forward end of the scow is suspended, by a framework, a double set of knives, each 
set being similar to those of mowing machines used by agriculturists. The object 
in having double knives is to enable the machine to cut when moving backward as 
well as when moving forward, thus avoiding the necessity of having to turn the 
scow around when the end of the swath is reached. The knife bar is 12 feet long 
and consequently cuts a swath 12 feet wide. The power of propelling the machine 
is supplied by a 6-horsepower high-pressure condensing engine, which is located in 
the middle of the scow. A line 1,000 feet in length is passed with three turns around 
a winch head and drawn taut by an anchor at each end, placed a short distance 
beyond the extreme boundaries of the area to be mowed. It is held in position by a 
fair-leader or chock having a shive on each side similar to the shive of an ordinary 
tackle block. The shives facilitate the passage of the line through the leader by 
lessening the friction and correspondingly decrease the wear upon it. The leader 
or chock is placed on the forward end of the scow, and not only serves to hold the 
line iu position, but also keeps the scow straight in its course. 

When the engine is started, the winch-head revolves, and the pressure of the line, 
encircling it in three turns tightly drawn, forces the scow through the water. The 
rate of speed at which it can be operated is 1,000 linear feet in 5 minutes, thus 
enabling it to mow an area of 2,000 square feet or more per minute, or 1 acre in from 
20 to 22 minutes, making allowance for time spent in moving anchors or otherwise 
adjusting the machinery. 

When fitted for work, with coal and water, and manned with three men, including 
an engineer, which is the number requisite to operate the machinery and attend to 
shifting the anchors, the draft of the scow is about 8 inches of water. When the 
anchors have once been adj usted, several swaths can be mowed before they require to 
be shifted over toward the uncut grass, as the line can not easily be drawn so taut — 
nor does it need to be — as not to allow the scow to be moved (pushed with a pole) 
sidewise for a short distance. When necessary, the anchors are shifted by the use of 
a small boat. Thus the scow is guided back and forth across the lot, cutting the 
grass with equal facility in both the forward and backward movements. When the 
grass is cut, it floats to the surface of the water and is carried away by the current. 
The knives are set in motion by a vertical iron shaft which passes through a hori- 
zontal cogged wheel. This wheel is geared to a pulley which is run by a belt from 
the engine. The vertical shaft is so arranged as to slip up or down in order to gauge 
the machine to any depth of water within the range of its capacity. The extreme 
depth of water in which mowing can be successfully done, as it is now adjusted, is 
about 8 feet. It could doubtless be so arranged as to operate in deeper water. 

If there are no obstacles in the way, the grass can be cut within 1 inch, of the bottom. 
If there are oysters on the ground, some allowance for that fact has to be made, 
and while the grass cannot be sheared so close to the bottom, it can be mowed 
sufficiently close to the oysters to answer all practical purposes. The only thing 
requisite is to mow it short enough to preclude the possibility of any large quantity 
of sediment settling in it and choking the oysters. This object is easily attained, as 
grass a few inches long will not injure the oyster crop. It is when its length is 
measured by feet aud it is filled with sediment that it becomes dangerous. 

In the locality where this machine is used the water is about 6 feet deep. It 
has been customary to mow the oyster-beds quite frequently, five or six times, 
perhaps, during the growing season, from the first of May to the last of October. The 
result has been that tracts of bottom that would have otherwise been worthless for 
oyster-growing purposes have been converted into beds as productive as any in the 
river. The cost of building a similar machine is estimated by Mr. Allen to be from 
$450 to $500.* 

* Hall, Ansley, Rept. U. S. Fish Commission 1892, pp. 477 and 478. 



320 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 
INCREASE ON PLANTED BEDS. 

The percentage of seed oysters which reach maturity depends upon 
local and seasonal conditions, upon the care with which the oysters 
have been planted and worked, the size of the oysters when planted, 
and the length of time which they have been left to lie. Under the 
very best conditions there is a considerable mortality among the plants, 
and while the individual oysters have increased greatly in size the loss 
from one cause or another is such that there is by no means a corre- 
sponding increase in the total quantity as measured in bushels. In some 
places the planter is satisfied if he can market a bushel for each bushel 
planted, depending for his profit upon the increased price brought by 
the larger growth, but the usual average yield in many localities is two 
or three times this amount, and cases are known where 500 bushels of 
shells yielded 3,000 bushels of salable oysters. 

GROWING OYSTERS IN PONDS. 

In Europe pond culture has been commercially successful for many 
years, and in some countries practically the entire product of oysters 
has been derived from this source. Small inclosed ponds, claires, have 
been used in France for greening and flavoring the oysters and parks 
or partially inclosed ponds, admitting the tides, are used for growing 
the oysters from seed, but all experiments heretofore made with a view 
of raising the seed in closed ponds have been attended with failure or 
scanty success. 

Over a large area of our oyster-producing territory the difficulty of 
obtaining seed is usually not a pressing one and an utter failure to 
secure a set is rarely confronted upon more than occasional years. 
Under such conditions, in several regions, the practice of sowing shells 
has grown to great proportions, but with the vast increase in the planted 
area an increasing difficulty has arisen in preparing the oysters for 
market. Growth is slower than formerly, and during some seasons the 
oysters either do not fatten at all or else so slowly that months are 
wasted before they can be brought into proper condition. It is signifi- 
cant that complaints of this difficulty come from regions which were at 
one time famous for the fatness and flavor of their product and that 
the trouble was not manifested until the population of the beds far 
outgrew that which was found in their natural condition. The causes 
leading to the difficulty complained of have never been studied, but 
the explanation will probably be found in the fact that the quantity of 
oysters in such regions has outgrown the ability of the waters to supply 
them with food. 

As is elsewhere pointed out, the rate of the growth depends primarily 
upon the relative richness of the food supply, and a quantity which 
may be sufficient to cause a moderate growth may still be inadequate 
to produce the degree of fatness upon which the oyster's toothsomeness 
so largely depends. 



OYSTERS AND METHODS OF OYSTER-CULTURE. 321 

It is manifestly impossible to propose efficient means for increasing 
the abundance of the food organisms over any very extended area of 
open waters, where ownership is vested in the many and the conditions 
are not subject to control. Only in inclosed or semi-inclosed bodies 
of water could there be any hope of such regulation of temperature, 
density, and other factors as to conform to the best conditions for the 
rapid multiplication of such organisms as constitute the preponderance 
of the oyster's food. If it were possible for the planter to have at his 
command a body of water extremely rich in food he could, in a short time 
and at will, fatten oysters which had grown to a marketable size upon 
other and less favorably situated beds. It is probable that under intelli- 
gent direction a comparatively small area could be made to serve as a 
fattening bed for all of the oysters produced on a great area of ordinary 
shelled ground, and that the cost of preparing and maintaining the rich 
food producing beds would be returned many-fold in the ready sale and 
high price which the superior product would be able to command. In 
many places in the United States this plan is followed with success by 
transplanting the oysters from offshore beds to harbors and coves, but 
so far as known no practical and conclusive test of culture in artificially 
prepared ponds has been made, and it is therefore not possible to give 
full and practical directions concerning the method to be followed in 
attempting it. 

The European methods are generally not economically adapted to 
use in our waters, but the experience of French culturists has estab- 
lished certain principles which are of general application, and may 
serve as a guide to those working upon somewhat similar lines here. 

There are many localities within the limits of the oyster-producing 
region of the United States where pond culture for the purpose of 
growing and fattening oysters would probably prove successful, and salt 
ponds, connected with tide water by natural or artificial channels, could 
often be made to return a good dividend to their owners if converted to 
the uses of oyster culture. In other cases low and swampy land might 
be dredged or excavated so as to answer the purpose, and thus be made 
to return a revenue in perhaps the only possible manner. Such ponds 
should be well protected by embankments sufficient to prevent the 
entrance of water except when desired, the supply being regulated by 
flood-gates which can be opened or closed at will, or the height of the 
embankments may be so adjusted that the water from the sea will enter 
during very high tides only, say once or twice a month. When the 
ponds are large it has been found that the surface aeration is sufficient 
to supply the oxygen required, but in smaller ponds it is necessary to 
attain this end by more or less frequent interchanges of water between 
the pond and the main body of salt water with which it is connected. 
In the case of practically inclosed ponds it is necessary to provide for 
the addition of fresh water to make good the loss occasioned by evap- 
oration. If this precaution be neglected the density of the water will 
rise above the maximum in which the oyster flourishes. 

F. C. I?. 1897 21 



322 REPORT OP COMMISSIONER OF FISH AND FISHERIES. 

It may be advisable in some places to reduce the density in the ponds 
below that of the open waters, as it is well known that the more brack- 
ish waters are generally most favorable to the rapid multiplication of 
diatoms and other minute vegetable forms valuable to the oyster-grower. 
Experiment could be made to demonstrate approximately the best 
density for the purpose, and where the water supply is under control 
the pond could be maintained at nearly or quite the degree of salinity 
required. The ordinary surface drainage into many natural salt ponds 
is sufficient to reduce the density below the level in the main waters, 
„and by merely regulating the inflow of sea water the grower will prob- 
ably find that almost any degree of brackishness may be maintained at 
will. Such ponds will be found to possess all the requirements for the 
production of food in abundance, the density will be favorable, their 
shallowness will cause them to warm early in the season, and thus 
stimulate the growth of microscopic vegetation, and their immunity 
from the influences of tides will prevent the carrying away of the food 
which they produce. 

There are, of course, many places where the natural conditions for 
the production of oyster food are all that could be desired, and there 
pond culture would doubtless be unnecessary, but in other localities, 
such as are mentioned at the beginning of this section, it seems to offer 
the most promising field for experiment. 

BREEDING OYSTERS IN PONDS. 

While in some of our most important planting regions there is rarely 
any difficulty in obtaining seed oysters, there are places, otherwise 
admirably adapted to the industry, in which the supply of seed is 
extremely precarious. The most remarkable fluctuations in the set of 
spat take place, and often where there is one year an abundance the 
following season may exhibit a dearth. In certain localities on Long 
Island a set of spat rarely occurs, and the planters long ago abandoned 
the attempt to raise seed and now procure it from some other region 
more favored in that respect. In still other places, as over the larger 
part of Chesapeake Bay, the seed oysters are obtained mainly from 
the natural beds, but with the depletion of these there will be an 
increasing difficulty in obtaining it, and before long it will no doubt be 
necessary to derive it from some other source. There is an increasing 
tendency in the region last mentioned to follow more closely the method 
of sowing shells practiced in Connecticut; in some places the experi- 
ment has met with great success so far as the procuring of a set is con- 
cerned, but in other localities the results are too uncertain to permit it 
to be followed with profit. 

Where a "strike" occurs each year with tolerable certainty this 
method is without doubt the best available to our oystermen, but where 
the spat may fail to set for several years in succession, the expense of 
putting down the shells without return will soon eat up the profits of 



Report U. S. F. C, 1897, (To face page 323.) 




Spawning Pond X. 



Section on Line A~A. 




Plate III. 






Section on Line B-B. 




5P#S^^ 



GROUND PLAN AND SECTIONS OF PONDS FOR SPAT-CULTURE. 
Adapted from John A. Ryder. 



cflSI 



OYSTEES AND METHODS OF OYSTER-CULTURE. 323 

more successful years, and the irregularity of his crop may cost the 
planter his market. 

It is obvious that in order to obtain more certain results the con- 
ditions upon which the spatting depends should be subject to some 
control. It is useless to expect such control in any adaptation of the 
ordinary method of planting shells, and the only direction which prom- 
ises success in such an attempt is some modification or form of pond 
culture. The culturists of Europe have shown that a very considerable 
control can be exercised over the conditions in parks used for growing 
oysters from seed, and with proper modifications the same success 
could doubtless be attained with breeding ponds for raising seed. 
"To actually come into competition with the system of shell sowing in 
deep water we must proceed to abandon all old methods, condense our 
cultch so as to have tbe greatest possible quantity over the smallest 
possible area, and finally have that so arranged that the currents devel- 
oped by the tides, in consequence of the peculiar construction of a system 
of spawning ponds and canals, will keep the cultch washed clean auto- 
matically. Unless this can be done, all systems of pond or cove culture 
for the purpose of obtaining spat must unhesitatingly be pronounced 
failures."* 

Impressed by these facts, Dr. Ryder, in 1885, devised a very ingenious 
method of spat-culture, which he described as follows : 

(A) The method as adapted to canals or sluices in which the cultch is placed in masses, 
with jetties at intervals. 

The first form in which I propose to inaugurate the new system of spat-culture 
which has grown out of the principles already developed consists, essentially, in 
condensing the cultch or collecting apparatus in such a way as to expose the maxi- 
mum amount of collecting surface for the spat to adhere to within the least possible 
area. This may be achieved in the following manner : A pond, X, as shown in plan 
and elevation iu plate in, is constructed with a long zigzag channel, s, connecting it 
with the open water. The pond ought to be, say, 40 to 60 feet square; the channel, 
s, may be, say, 3 feet 3 inches wide, as shown in the diagram. The vertical banks, 
z, between the zigzag canals running to the open water might be 3 feet in width. 
The sides of the canals ought to be nearly or quite vertical, and the earth held in 
place with piles and rough slabs or planks. The direct inlet to the pond at /might 
be provided with a gate, and the outlet of the canal, where the latter connects with 
the open water at o, might be provided with a filter of moderately fine galvanized 
wire netting and a gate; the first answering to keep out large fish and debris and 
the latter to close under certain circumstances, or when violent storms develop 
strong breakers. The accompanying plan and sectional elevation, as shown in plate 
in, will render the construction of such a pond and system of collecting canals clear. 

Into the pond, X, I would put an abundance of spawning oysters, say 100 bushels, 
if the pond were 40 feet square, and 200 bushels if it were 60 feet square. But 
instead of throwing the oysters directly upon the bottom, I would suggest that a 
platform, of strong slats be placed over the bottom of the pond at a distance of 
8 to 10 inches from the earth below, upon which the oysters should be evenly dis- 
tributed. This arrangement will prevent the adult oysters from being killed by 
sediment, and also afford a collector, in the form of a layer of shells, to be spread 



* Rept. U. S. F. C. 1885, p. 392. 



324 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 

over the platform, and give the fry a better chance to escape without immediately 
sinking into the ooze below. 

The mean depth of water in the pond and canals ought not to be less than 3£ feet 
and the bottom of the pond and canals should be cut to the same level, with a view 
to get the full benefit of the tides. 

The method of operating such a system will now be explained. The pond, A 7 , is 
supplied with the above specified quantity of good spawning oysters, which at a low 
estimate ought, at the rate of 50 females per bushel, to yield from 100,000,000,000 to 
200,000,000,000 of fry during the time the cultch may be in position in the canals. 
If, however, the oysters were very large selected ones, fully twice as much fry ought 
to be thrown out by them, or fully 200,000,000,000 to 400,000,000,000. 

This enormous quantity of embryos must, unless it finds some objects to which to 
attach itself, be irrevocably lost. In order, therefore, to provide it with a nidus for 



— \L. 



— it 




Cut 6. — Receptacle for cultch. 



the purpose of fixation, an extensive system of collectors is provided in the chan- 
nel, s. These are figured in detail above, the first being an end and the second a 
side view and the third a plan. These are essentially flat baskets, with wooden 
ends, and with the bottoms and sides formed of a very coarse kind of galvanized 
iron wire netting with 1 to 1$ inch mesh. At the top they are open, and on either 
side a strong strip or scantling is secured and projects out past the ends of the box 
or receptacle, to afford a means of supporting the whole upon scantling or ledges 
secured near the tops of the sides of the canals, s. These projections of the strips 
are also intended to afford handles by which two men may lift and move the 
apparatus about. The uprights at the ends and the horizontal crossbars are intended 
to enable the culturist to vibrate the box and its contents in the water of the 
canal without lifting it out, and in such a way as to wash off any injurious accu- 
mulation of sediment not swept away by the action of the jetties presently to be 
described. 



OYSTERS AND METHODS OF OYSTER-CULTURE. 325 

These baskets or receptacles are open at the top and are intended to be filled with 
clean oyster or clam shells as cultch for the spat. They are each to hold about 3 
bushels of shells, a quantity as large as can be conveniently handled by two men. 
One hundred of tbese will therefore contain 300 bushels of cultch, though I actually 
believe that 400 such boxes, or 1,200 bushels of cultch, through which sea water 
charged with fry thrown off by 100 bushels of spawning oysters would pass, would 
not afford too great an amount of spatting surface, because we have shown on the 
basis of actual observation that a body of water adapted to oyster-culture is capable 
of yielding spat throughout all of its three dimensions. 

These boxes or frames, after they are filled with the cultch, are suspended in the 
canals, the cross section of which they should nearly fill at low tide. They are placed 
with their widest dimension across the canal, so that during the rise and fall of the 
tide the water has to rush through them no less than four times daily, and as the 
water is thoroughly charged with embryos, the greatest possible opportunity is 
afforded the young fry to affix itself. 

In order to still further guard against the accumulation of sediment it is proposed 
to place jetties across the canals. These may consist of boards, forming a frame, 
which may slide into or be secured by vertical ledges fastened to the sides of the 
canal. These jetties may have one or two wide vertical slots in them, through 
which the tide will be compelled to flow with augmented velocity, and thus scour 
the sediment off of the cultch contained in the suspended boxes or frames on either 
side of them. Such jetties may be placed at intervals along the canal, and they 
might be made movable, so as to be changed in order to affect other sets of boxes of 
cultch at other points along the sluice. 

The system of canals, as shown in the plans, should hold about 400 receptacles filled 
with shells, or at least 1,200 bushels of cultch. In practice I think it probable that 
even a longer system of canals will be found available; but it must always be borne 
in mind that the area of the pond must not very greatly exceed the total area of the 
system of canals, or else so much more water will run out of the pond at every ebb 
of the tide that a great many embryos will be carried past the system of collectors 
in the canals into the open water and be entirely lost. There is, consequently, a 
very good reason for having the areas of the two nearly equal. 

The preceding system of culture, it will be obvious, is only an application of 
principles well established and based upon the observation of the actual behavior of 
oysters under natural conditions, as observed at Fortress Monroe, St. Jerome Creek, 
Woods Hole, Cohasset, and Long Island Sound. 

The spawning ponds, after the season is over, may be used for fattening choice 
oysters for market, as they will actually hold about the quantity stated at the outset 
of tnis chapter. They may also be used in connection with another modification of 
the method of using cultch much crowded together or condensed, to be described 
later on. 

The cultch may, without harm to the spat, be allowed to remain in the suspended 
receptacles in the canals until the first or middle of October, when it should be taken 
out and spread upon the bottom on the open beds where it is to grow larger. The 
reason for allowing the cultch to remain so long in the boxes is because spatting 
under favorable conditions continues for not less than ninety days, or from July 1 to 
October 1, so that all of this plant should be in working order by the 1st of July. 

-Jf # * TV * * * 

What we must do to-day is to adapt such means to the solution of the oyster prob- 
lem as will render them applicable in practice. The American cultivator does not 
get the price obtained by the French or Dutch oyster-farmer, nor can he for a long 
time to come expect to, for the reason that the aggregate area upon which the Ameri- 
can oyster is cultivated or indigenous exceeds by many times that upon which the 
European species is either native or cultivated. The European methods of using 
cultch, such as tiles, slates, brush, fagots, etc., are too expensive, too elaborate, for 
our practical people. We must reap in quantity what they reap out of the high 



326 EEPORT OF COMMISSIONER OF FISH AND FISHERIES. 

price of their product. Under the circumstances there is no possible way of solving 
the greatest question which now exercises the oyster-growers of this country but 
to put into their hands a method by the aid of which they can get all the spat they 
want on their own lands and from the spawn of their own oysters. 

******* 

The advantages of the method of using the cultch in concentrated bodies, giving 
an enormous amount of surface for the spat to adhere to, are that it can be 
conducted on the land owned by the culturist himself and with the spawn thrown 
off by the oysters belongiug to him. He is, therefore, not bound by any arbitrary 
oyster laws now existing to conform to what are, generally speaking, very inefficient 
and often absurd conditions. The new method puts it in the power of the culturist 
to rear his own seed for planting, and if he is so disposed he may put down an 
excess of cultch, which he can sell after it is covered with spat to the owners of the 
open beds in his vicinity. It involves comparatively little outlay to put down a 
plant which will accommodate 5,000 bushels of cultch, or enough to seed from 20 to 
30 acres for the first year. Such a system would be of great practical utility in the 
region of the Chesapeake Bay, where there are very extensive areas upon which, 
with very inexpensive excavation, the plant for conducting this method of culture 
could be organized. 

The plan of the small establishment given in the preceding pages is to be regarded 
as typical. In the use of the system with crowded or condensed cultch in different 
localities, modifications of the typical plan may often be advantageously employed. 
For example, an oyster-planter may have a large pond of 2 or 3 acres thickly 
planted with spawning oysters and connected with the open water by way of a 
narrow canal. The pond, if it has a firm bottom over its whole extent, may, if not 
already used for the purpose, be planted throughout with good seed or "plants," 
which, in the course of two years, will be mostly well-grown, marketable oysters. 
In such a case, several systems of canals could be fed from the single largo inclosure ; 
that is to say, instead of having only a single canal, several zigzag canal systems, 
each 3 feet in width, might be made to carry the water flowing in and out of the 
large inclosure, instead of the original channel, which might then be filled up and 
closed. Or, if it were practicable, the channel connecting tbe natural pond with 
the open water might be utilized for the same purpose as artificially constructed 
canals, provided the cost>of modifying it for the purpose were not too great. In 
some cases, by digging, filling, and dredging, as might be indicated in the course 
of such a natural channel, it could be prepared for the reception of cultch. Were 
such a channel wide enough, a system of parallel rows of light piles, the rows 
being 3 feet 3 inches apart and running lengthwise throughout the course of the 
channel, might be used to support the receptacles for the cultch, the latter being of 
the form used in tbe design of the typical system and supported, as in the latter, 
upon ledges or scantling spiked horizontally to the rows of piles just below the 
level of low tide. 

In other cases wbere there existed narrow points in the course of such a canal 
these might be used as jetties, still further narrowed in some cases, perhaps, by fill- 
ing in the sides, after which a system of parallel rows of piles with their horizontal 
supports of scantling might be constructed between the jetties, and upon which the 
receptacles filled with cultch could be supported. In this way the fry now dis- 
charged by spawning oysters from coves through their outlets, sometimes by the 
thousands of billions annually, can be caught upon cultch and permitted to develop 
into available spat. 

In many cases the cost of digging out the proper channels or canals to be used in 
the system of applying the cultch in concentrated form would be greatly diminished 
by the nature of the ground upou which the canals were dug out. If the level of 
the earth is not much above that of high water, so much the better, for then the 



OYSTERS AND METHODS OF OYSTER-CULTURE. 327 

labor to be expended in making the necessary excavations will be proportionally 
diminished, and no assistance from a skilled engineer will be required. 

Whether the spawning pond is excavated or not, the principle upon which the 
system is constructed and operated remains the same, namely, that the area of the 
canal systems and the ponds be about the same. In order that the fry be not car- 
ried past the collectors, the area of the pond should not much exceed the total area 
of the canals. In order that the fry may be wafted to the outermost collectors, the 
area of the canal system ought not to greatly exceed that of the pond or ponds. 

Canals constructed between a series of spawning ponds may also be utilized; in 
fact, a great many other modifications of the system are available, which would 
become apparent only after a study of a given location. The plans for carrying out 
this system would, in fact, have to conform to the demands of the location, so that it 
may be said that each establishment would have to be designed in conformity with 
local conditions. 

If cultch in the form of shells is the best (for which conclusion we have assigned 
reasons), it follows that such material should be so utilized as to obtain the largest 
possible return for the least possible outlay. In other words, if shell cultch is to be 
used at all, let it be expeditiously and economically, and not wastefully and 
unscientifically, employed. It has been found that even the sowing of shells is 
profitable, as has been conclusively demonstrated, and in one type of culture, 
namely, that which is practiced in deep water, it is probable that it is the only 
practicable method which will be devised for a long time to come. While it is to a 
great extent wasteful and at times uncertain, for the present, at least, there seems 
to be no other which can be so economically and successfully operated over large, 
open, navigable areas. Large areas operated by one individual or corporation can 
not always be commanded, or only exceptionally, under the existing laws of the 
States of Maryland and Virginia. In those States, however, where it is possible to 
command the right to natural areas of water which are more or less nearly land- 
locked, the system of merely sowing shells would be positively wasteful and not in 
conformity with the results attainable under the guidance of the proper knowledge. 

It is found in the practice of shell sowing that extensive areas will sometimes fail 
to produce any spat. This is apparently due to the presence of currents which have 
swept the fry off the beds, or to the presence of sediment, which has put an end to 
the first stages of its'fixed career. Even after the spat is caught, great destruction 
may occur through the inroads of starfishes, or a too rapid multiplication of worm 
tubes over the cultch and spat. The latter is sometimes smothered in vast numbers 
from the last-mentioned cause, as has been recently discovered by Mr. Rowe. Such 
casualties are rendered either impossible or readily observable during their early 
stages by the method of inclosing the cultch in suspended receptacles, as suggested 
in this paper. The netting -will effectually protect the young spat against the attacks 
of large starfishes, and no growth of barnacles or tunicates, worm tubes or sponges, 
would be rapid enough during the spatting period, judging from an experience 
extendiug through several seasons, to seriously impair the spatting capacity of the 
cultch used in the suspended receptacles. Any of the larger carnivorous mollusks, 
fishes, or crustaceans which could prey on the young oysters can also be barred out 
and kept from committing serious depredations by means of the netting around the 
cultch, as well as by means of screens placed at the mouth of the canal. 

The maximum efficiency of the cultch is not realized in any of the old forms of 
collectors, for the reason that the cultch can not be kept clean; secondly, because 
both sides of the cultch can not be exposed to the passing fry ; thirdly, because the 
fry can not be compelled to pass over and amongst the cultch repeatedly; fourthly, 
because the cultch is scattered over too great an area and throughout only two 
dimensions of a body of water, namely, its horizontal extent, where it is possible, as 
I have shown above, to do all this and more — that is, to avail ourselves of the possi- 



328 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 

bility of obtaining spat through the three dimensions of a body of water charged 
with embryo oysters in their veliger condition. These are good and sufficient 
reasons for my assertion that cultchhas hitherto been wastefully and unscientifically 
applied. With this I must conclude this exposition of the principles of a rational 
theory of oyster-culture, a subject which has received the attention of many investi- 
gators, none of whom have, however, struck at the root of the question and allowed 
themselves to be guided by readily verifiable facts. In the hope that I have made 
both the theorj 7 and the practice of my new method clear to the reader, who, if he 
should happen to be an oysterman, will, I hope, at least give me the credit of being 
honest and sincere in my intentions, and, whether ho feels inclined to ridicule or to 
adopt my conclusions, I feel very certain that what I have formulated in the preced- 
ing pages will become the recognized doctrine of the future. * 

A trial of this method was made by the Fish Commission at St. 
Jerome Creek, Maryland, but it was found that Dr. Eyder's expecta- 
tions regarding the freedom of his apparatus from sedimentation were 
unfounded. St. Jerome Creek is admirably adapted, from its rich food 
supply, to growing oysters from seed, but its very advantages in this 
respect militated against the success of the experiment of spat-raising. 
A small set was obtained upon some of the cultch exposed, but the 
deposit of sediment was so rapid that the young oysters were unable 
to fix in quantities sufficient to make the experiment a commercial 
success. 

It seems probable that under more favorable conditions with respect 
to sedimentation the apparatus would prove a useful one, and it is to 
be hoped that it will be given a further trial. The writer witnessed 
Dr. Eyder's experiment at Sea Isle City, IS. J., with a modification of 
this arrangement, and, although the trial was made on a scale too 
small, the results were such as to impress him with the feasibility of 
the device under more favorable conditions than existed at St. Jerome 
Creek. 

One of the principal defects in Dr. Eyder's apparatus appears to be 
the lack of suitable arrangements for flushing the cultch with currents 
of water sufficiently strong to scour away any sediment which may accu- 
mulate. It was supposed that this could be accomplished by means of 
jetties, but the current induced in the long canal by the ebb and flow 
of the tide is apparently too gentle to have the effect sought. This end 
might be gained by providing the inner loops of the canal with gates 
communicating with the pond, the outer loops having similar means 
of communication with the exterior waters, as shown in plate in, 
which is adapted from Dr. Eyder's plans. If the water in the pond at 
high tide be held back until the canal has nearly emptied, a strong cur- 
rent could be directed into any loop by opening the appropriate gates. 
On the other hand, if the gates at the outer end of the loops be closed at 
low water, a strong current could be thrown into the canals by opening 
them at high water. By thus occasionally flushing each pair of loops 
in succession it is believed that the injurious collection of sediment 
can be prevented in even quite muddy water. The end is accomplished, 

* Rept. U. S. F. C. 1885, pp. 381-423, pis. i-iv. 



OYSTERS AND METHODS OF OYSTER-CULTURE. 329 

however, by some loss in simplicity of construction and operation of 
the apparatus and at the expense of the escape of some of the embryos. 
Plate in shows the original plans modified by the addition of sluice- 
gates. 

It is thought that this method of utilizing cultch may solve the 
problem of the culture of the eastern oyster upon the Pacific coast. 
Two chief difficulties there interfere with the obtaining of a strong set: 
the temperature of the water is in most places too low to insure active 
spawning, and, secondly, the young of the imported species is crowded 
out by the rank growth of the native oyster. It is probable that both 
of these difficulties might be overcome by the use of Dr. Byder's method 
or some modification thereof. There is little doubt but that the ebb 
and flow of the tides through the channels could be so regulated that 
a sufficient quantity of water would remain at low tide to temper that 
which would flow in at flood tide. The shallowness of the pond should 
render it so susceptible to the effect of the sun's rays that a tem- 
perature several degrees higher than that of the neighboring water 
could be maintained, and in some places these two or three degrees 
are perhaps the measure between success and failure in obtaining a set 
of spat. 

The eastern oyster spawns at 67° or 68° F., but does better at 70°. 
Ponds such as that described might be located in connection with the 
sloughs communicating with the bays, and, as Mr. 0. H. Townsend 
says that the native Pacific coast oyster does not flourish in such 
places, the imported species would doubtless have a better opportunity 
of survival during its early career, the period when it is especially 
liable to suffocation by foreign organisms. If necessary, a filter, such 
as is described on pp. 330-332 of this paper, might be introduced into 
the mouth of the canal. This would to some extent interfere with 
the ebb and flow of the tides between the pond and the slough or bay, 
but it might be the very thing necessary to retard the interchange 
sufficiently to allow the water in the pond to become warmed by the 
sun. 

The experiment is at least worthy of a trial, and it may be the means 
of saving to the planters of the Pacific coast the large sums of money 
which are now annually expended in transporting seed oysters across the 
continent. The experimenter, if successful, would reap the benefit of 
his own success. The brood oysters used in stocking the pond should 
preferably be plants of several years' standing, as such would be more 
likely to be acclimated than those brought from the East but a short 
time prior to the experiment. 



330 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 



ARTIFICIAL PROPAGATION. 

Artificial propagation in the fish-culturist's sense, the raising of 
oyster fry from artificially fertilized eggs, has, at the present time, no 
place in practical oyster- culture. It may perhaps sometime demon- 
strate its applicability to a system of spat production in small closed 
ponds, but it can have absolutely no use in the present methods of 
oyster- growing. It is futile to expect any results from deposits of the 
swimming fry upon beds planted in the open waters of the bays and 
sounds where the conditions are usually such as would bring about a 
wide distribution. Fry so deposited would be, no doubt, largely carried 
to other beds, and be lost to the man who planted them, or else would 
fall upon unsuitable bottom. Their fate after being deposited in the 
water is so uncertain that, in our present state of knowledge, it 
would be a waste of effort for either Government hatcheries or private 
individuals to attempt to increase the oyster by such means. 

If, however, there can be devised some successful method of closed- 
pond production, then artificial propagation may find a field of useful- 
ness. Dr. Eyder suggested that the available amount of fry in his 
method of spat-culture might be increased by adding embryonized 
water to the inlet to the sluice at the beginning of flood tide, the 
embryos being carried up through the cultch upon the flood and back 
again upon the ebb, thus giving a double chance for fixation. There 
is no doubt but that the proportion of eggs successfully fertilized can 
be increased by the artificial mixture of the ova and spermatozoa 
according to methods which science has demonstrated. 

Another experiment by the same investigator showed that spat could 
be raised in a practically closed pond from artificially fertilized eggs. 
The experiment was' briefly as follows: The pond was excavated in the 
salt marsh on the shore of Chincoteague Bay. It was about 20 feet 
square and 3£ feet deep, and communicated with the bay by a canal 10 
feet long, 2 feet wide, and the same depth as the pond. The mouth of 
the canal was closed with a filter composed of boards perforated with 
auger-holes and lined inside with gunny-cloth or bagging. The boards 
constituted two diaphragms, an inner and outer, the interval of 2 inches 
between being filled with clean sharp sand. Through this the tide 
ebbed and flowed, giving a rise and fall of from 4 to 6 inches during 
the interval between successive tides. 

This filter, like most structures of its class, showed a tendency to 
clog after it had been in use for some time, and as, from its shape, it 
was difficult to cleanse, Dr. Eyder devised the following arrangement, 
which is accessible at all times and in which the sand may be renewed 
at will: 

My improved permeable diaphragm is placed horizontally within an oblong 
trunk or box, A, fig. 1, of plate IV. The box is made of inch planks, to which strong 
horizontal sidepieces, a, figs. 2 and 3, are secured, and to which are fastened the 



.Report U. S. F. C. 1897. (To face page 330.) 



Plate IV. 




Flg.1. 





Tig.2. 



Tig-3. 



T- 



\:',' !■';[,] 



-_ — J! 




Jig A. 



DETAILS OF FILTER FOR PONDS USED FOR OYSTER-CULTURE. 
After John A. Ryder. 



OYSTERS AND METHODS OF OYSTER-CULTURE. 331 

transverse crossbars i i, of rigs. 1, 2, 3, and 4, upon which the permeable diaphragm 
rests. Fig. 1 represents the trunk A secured within a pair of quadrangular frames, 
F F, and partially in sectional elevation in place in the trench or canal leading from 
the pond to the open water; fig. 2 represents the construction of the end of the trunk 
next the open water, and fig. 3 that of the end next the pond, while fig. 4 shows the 
trunk as viewed from above. 

On the crossbars b b a single screen of galvanized wire cloth, W, fig. 1 (galvan- 
ized after it is woven), is superimposed, having meshes, say, one-half inch in diameter; 
upon the wire screen a layer of gunny-cloth, C, figs. 1 and 4, is laid, upon which a 
layer of fine, clean sand, S, is spread evenly from one end of the trunk to the other. 
The end board e, extending halfway up at the outer end of the box, runs up past 
the level of the wire and cloth to confine the sand at that extremity, as shown in 
fig. 2, while the sand is confined by the board i at the other end of the trunk next 
the pond, as shown in fig. 3. The wire cloth and bars b b constitute the support 
for the sand as it lies upon the gunny-cloth, which is supported in turn by the wire 
cloth or screen W. This is essentially the construction of the filtering apparatus in 
which the layer of sand, S, is at all times accessible, so that it can be removed if it 
becomes clogged with ooze carried in by successive tides under the gate G, figs. 1, 
2, and 4. This layer of sand can also be increased or diminished in thickness so as 
to strain the inflowing and outflowing water more or less effectually, as may be 
desired, or in order to more or less effectually prevent the escape of any eggs or 
embryos of oyster which may be developing within the pond and wafted to and fro 
by the ebbing and flowing currents which are carried in and out of the pond through 
the diaphragm by tidal action. The gunny-cloth, C, fig. 4, may possibly be replaced 
by, first, a layer of coarse gravel, then a layer of finer gravel superimposed upon 
that, which would prevent the fine sand from sifting through the supporting wire 
screen W. Gravel would be more durable than gunny-cloth or sacking, which, like 
all other textile fabrics, will rot if immersed in salt water for a few weeks. In 
practice, however, a mode of getting over all such difficulties would soon be devised. 
A coarse sacking to be used for the purpose might be saturated with a drying oil or 
with tar diluted with oil of turpentine, which when dry would act as a preservative 
of the material, but not cause it to become impervious. 

* * * * * ~r * 

When the trunk A is put in place (which should be done before the water is let 
into a freshly excavated pond, and also before the water is let into the trench from 
the sea end), it should be securely placed in position and the earth tightly rammed 
in along the sides so as to prevent any sea water from finding its way into the pond, 
except such as passes through the filtering diaphragm. It is also unnecessary to 
insist that the trunk be constructed in such a way that it will be practically water- 
tight, and not liable to leak between the planks or at the corners. The wire cloth, 
sacking, or gravel, and sand having been got into place, and when complete forming 
a stratum having a total thickness of 5 or 6 inches, the operator is ready to cut 
away the barrier at the sea end of the trench and let in the water. 

If then the trunk A has been let down into the trench deep enough the sea level 
at low tide ought to be somewhat above the upper edge of the board e. The water 
will then, as the tide rises, flow back over the sand as far as the board i, and will per- 
colate throngh the diaphragm into the space I, under the latter, and so find its way 
into the pond. After a day or so the pond will be filled with sea water which has 
practically been filtered, and filtered more or less effectually in proportion to the 
thickness of the stratum of sand constituting the diaphragm. After the pond has 
once been filled with the rise and fall of the tide in the open water the level of the 
latter and that in the pond will be constantly changing ; in other words, when the tide 
is ebbing the water level in the pond will be higher than that of the water outside, 
as in fact represented at wl and tl in fig. 1. Under these circumstances there will 
be a supply of water flowing out through the under division I of the trunk A, up 
through the sand and out over its surface through the outlet under the gate G. 
After the ebb tide is over and flood tide begins these levels will be reversed and wl 



332 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 

in the pond will be lower than tl in the open water, and under those circumstances 
there will he an inflow of sea water into the pond through the diaphragm instead of 
an outflow, as is the condition of the water level during ebb tide. Under such condi- 
tions there will be four alternating periods during every twenty- four hours of inflow 
and outflow, lasting, we will say, four hours each, not reckoning the nearly stationary 
intervals between tides or during slack water. This almost constant partial renewal 
of the water will unquestionably maintain the water inclosed in the pond or ponds 
by means of diaphragms in a condition fitted to support oysters colonized therein, 
provided its density is not too great or too slight, and if there is also some micro- 
scopic vegetation present. 

It will be readily understood from the preceding description how it is intended 
that the apparatus is to be operated. The figures also give a very good idea of how 
the diaphragm and trunk are to be constructed, the first four figures being drawn 
to a common scale of 1 inch to 3 feet.* 

The water in the pond remained at about the same density and tem- 
perature as that in the open bay and soon developed a greater abun- 
dance of food organisms, both plants and animals. Artificially fertilized 
ova were placed in the pond at intervals during the spawning season, 
and forty-six days after the beginning of the experiment young spat 
from one- fourth to three-fourths of an inch long were found attached 
to the bunches of shells which had been hung upon stakes to serve as 
collectors. Great difficulty was experienced from sedimentation. The 
experiment demonstrated that spat could be raised in ponds from 
artificially fertilized eggs and that it would grow as rapidly as the spat 
reared in the open bay. As the conditions are stated by Dr. Ryder, it 
appears probable that equally good or better results might have been 
attained with less labor by placing a quantity of spawning oysters in 
the pond. 

Not only would there be a saving of labor in the direct use of the 
spawning, oysters, but there would also be no necessity for the sacrifice 
of the parents, as must be done under the method of artificial fertiliza- 
tion. The increase in the size of the spawners under the favorable 
conditions of growth would probably go far toward the payment of 
expenses. 

The method which promises the best results is that in which the eggs 
are deposited in the pond within from three to five hours after fertili- 
zation. There is apparently nothing to be gained in holding the eggs 
a longer time, the chief gain of the culturist being not in the protection 
of the embryo, but in the increase of the proportion of eggs fertilized. 

The method of fertilization used by Dr. Eyder was as follows : 

The method formerly used was to first learn the sex of a number of adult oysters 
with the microscope, then cut out the generative glands with their products and 
chop up those of different sexes separately in small dishes with sea water. This 
system we may now say is barbarous, because it is crude. Large numbers of eggs are 
destroyed by crushing, or are injured by the rough usage to which they are subjected, 
and, besides, there is no assurance that the eggs or milt operated with are quite 
mature. It is also troublesome to free the generative gland from fragments of the 
liver, which help to pollute the water in the incubating vessels with putrescible 

*Bull. U. S. F. C. 1884, pp. 19, 21, 22, 23. 



OYSTERS AND METHODS OF OYSTER-CULTURE. 333 

organic matter, and thus interfere greatly with the life and healthy development of 
the embryos. 

By our method the objectionable features of the old plan, as stated above, are 
overcome. If possible select good-sized oysters ; open them with the greatest possi- 
ble care so as not to mutilate the mantle and soft parts. Carefully insert an oyster 
knife between the edges of the valves and cut the great adductor muscle as close as 
possible to the valve which you intend to remove, leaving the animal attached to 
the other valve, which, if possible, should be the left or deepest one. The soft parts 
being firmly fixed or held fast by the great adductor muscle to the left valve pre- 
vents the animal from slipping under the end of the pipette, held flatwise, as it is 
gently and firmly stroked over the generative gland and ducts to force out the 
generative products. 

To prepare the animals to take the spawn from them after opening, the following 
precautions are to be observed : Note that the reproductive gland in great part 
envelops the visceral mass and extends from the heart space, just in front of the 
great adductor, to within a half inch or so of the head or mouth end of the animal, 
which lies next to the hinge. Note also that both sides of the visceral mass which 
incloses the stomach, liver, and intestine are enveloped on either side by a membrane 
which also lies just next the shell and is garnished by a fringe of purplish, sensitive 
tentacles along its entire border except at the head end, where the mantle of the left 
side passes into and is continuous with that of the right side of the animal. The 
ventral or lowermost side of the animal, anatomically speaking, is marked by the 
four closely corrugated gill plates or pouches, which are preceded in front by the 
four palps or lips, but both the gills and palps depend downward between the lower 
borders of the mantle of the right and left sides. Note, too, that if the mantle is 
carefully cut and thrown back on the exposed side of the animal between the upper 
edges of the gills and the lower edge of the cut or exposed end of the great adductor 
muscle, the lower and hinder blunted end of the visceral mass will be exposed to 
view. It is on either side of this blunted end of the visceral mass between the upper 
edge of the gills and lower side of the great muscle that the reproductive glands 
open almost exactly below the great adductor. From these openings we will after- 
wards find, if the animal is sexually mature and the operation is properly conducted, 
that the spawn will be forced out in a vermicular, creamy white stream. But in 
order to fully expose the reproductive organ we should carefully continue to sever 
the mantle of one side with a sharp penknife or small scissors some distance forward 
of the great muscle toward the head, cutting through the mantle just above the 
upper borders of the gills and following a cavity which lies between the latter and 
the lower border of the visceral mass. 

A little experience will teach one how far it is necessary to carry this incision of 
the mantle. For some distance in front of the heart space the mantle is free or 
detached from the visceral mass and reproductive organ, which lies immediately 
beneath, and this enables one, if the last-described incision has been properly made, 
to almost completely expose the one side of the visceral mass and the richly tinted, 
yellowish-white reproductive gland which constitutes its superficial portion. The 
opening of the gland and its superficial ramifying ducts being laid bare on the 
exposed side of the animal, we are ready to press out the spawn on that side. Before 
beginning this, however, it is important to observe that the principal duct passes 
down just along the edge of the visceral mass where the latter bounds the heart 
space, in which the heart may be observed to slowly pulsate, and that this great duct 
ends somewhere on the surface of the ventral blunted end of the visceral mass (plate i, 
fig. 2 d). To expose the great or main generative duct it may be necessary to cut 
through or remove the pericardial membrane which incloses or covers the heart space 
on the exposed side. If the oyster is sexually mature, the main duct will be observed 
to be distended with spawn, and that, originating from it and branching out over 
almost the entire surface of the visceral mass, there are minor ducts given off, which 



334 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 

again and again subdivide. If these are noted and it is observed that they are 
engorged, giving them the appearance of a simple series of much-branched great 
veins filled with creamy white contents, it may be certainly presumed that your 
specimen is mature and that spawn may be readily pressed from it. 

The operation of pressing the spawn out of the ducts requires care. The side of 
the end of the pipette may be used, being careful not to crush or break open the 
ducts as you gently and firmly stroke the pipette flatwise over the side of the 
visceral mass backward from the hinge toward the heart space and over the great 
duct at the border of the latter diagonally downward and backward to the opening 
of the reproductive organ. If this has been properly done it will be found that the 
generative products are being 'pushed forward by'the pipette through the ducts, as 
the pressure will be seen to distend the latter, the contents of the branches flowing 
into the larger and larger trunks until they are forced outward through the main 
duct and opening below the great adductor, where they will pour out in a stream 
one-sixteenth of an inch or more in diameter if the products are perfectly ripe. The 
sexes may be discriminated as described at the outset, and it is well to first find a 
male by the method already given and proceed to express the milt as described 
above into, say, a gill of sea water, adding pipetteful after pipetteful until it acquires 
a milky or opalescent white color. As the milt or eggs are pressed out of the open- 
ing of the ducts, they are to be sucked up by the pipette and dropped into the water, 
the mixture of milt being first prepared, to which the eggs may be added as they 
are expressed from the females. The judgment of the operator is to be used in mix- 
ing the liquids; in practice I find that one male will supply enough milt to fertilize 
the eggs obtained from three or four females, and it does not matter if the operation 
takes from twenty to thirty minutes' time, as the male fluid, which it is best to 
prepare first, will retain its vitality for that period. 

It is always desirable to be as careful as possible not to get fragments of other 
tissues mixed with the eggs and milt, and the admixture of dirt of any kind is to be 
avoided. To separate any such fragments nicely, I find a small strainer of coarse 
bolting or cheese cloth to be very convenient. 

In the foregoing description we have described the method of obtaining the spawn 
only from the side of the animal exposed in opening the shell. A little experience 
will enable one to lift up the head end of the animal and throw it back over the great 
adductor muscle, expose the opening of the reproductive organ on the left side, 
or whatever the case may be, and also express the spawn from that side, thus as 
effectually obtaining all of the ripe eggs or milt as is possible in the process of 
taking the same from fishes. 

It is remarkable to note the success attending this method, since almost every egg 
is perfect and uninjured, the percentage of ova, which are impregnated, is much larger 
than by the old method, reaching, I should say, quite 90 per cent of all that are taken 
when the products are perfectly ripe. It is also found that the products are not so 
readily removed by my process if they are not perfectly mature, which is also to 
a certain extent a safeguard against poor or immature spawn. In the course of 
an hour after the products of the two sexes have been mingled together it will 
be found that nearly every egg has assumed a globular form, has extruded a polar 
cell, lost the distinct germinative vesicle and spot in the center, and begun to develop. 

It is noteworthy that our practice as herein described has completely vindicated 
the statement made by the distinguished French anatomist and embryologist, M. 
Lacaze-Duthiers, that there is but a single generative opening on each side of the 
visceral mass of the oyster, and that, as we have«tated, it is found to open just below 
the great adductor muscle. 

We have also discovered, since the foregoing was written, that the use of an 
excessive amount of milt is of no advantage. The water in which the eggs are to be 
impregnated only requires to be rendered slightly milky; a very few drops of good 
milt is sufficient to make the impregnation a success. Too much milt causes the eggs 



OYSTERS AND METHODS OF OYSTER-CULTURE. 335 

to be covered by too large a number of spermatozoa; thousands more than are 
required if too much is used. These superfluous spermatozoa simply become the 
cause of a putrescent action, which is injurious to the healthy development of the 
eggs. A drop of milt to 20 drops of eggs is quite sufficient. 

Immediately after the ova have been fertilized it is best to put them into clean 
sea water at once, using water of the same density as that in which the adults grew. 
If the attempt is made to impregnate the eggs in water much denser than that in 
which the adults lived, it is probable that the milt will be killed at once. This 
singular fact, which was accidentally discovered by Colonel McDonald and myself, 
shows how very careful we should be to take into consideration every variation in the 
conditions affecting a biological experiment. If sufficient water is used no trouble 
will be experienced from the pollution of the water by dangerous micro-organisms, 
which are able to destroy the oyster embryos. From 50 to 200 volumes of fresh, 
clean water may be added to the volume in which the eggs were first fertilized. 
This may be added gradually during the first twenty-four hours, so as to assist 
aeration and prevent the suffocation of the embryos. * 



ARTIFICIAL FEEDING. 

There is no practical way now known of furnishing oysters with an 
artificial food supply. 

Experiments have been made with a view to feeding the adult oysters 
upon corn-meal or some similar substance, but such attempts have been 
of no practical value. There is no doubt that they would eat corn-meal 
or any other substance in a sufficiently fine state of division to be acted 
upon by the cilia. The oyster is incapable of making a selection of its 
food, and probably any substance, nutritious, inert, or injurious, would 
be swept into the mouth with complete indifference except as to the 
result. Corn-meal and similar substances would doubtless be nutri- 
tious, but their use must be so wasteful that the value of the meal 
would be greater than that of the oyster produced. 

The only way in which the amount of oyster food can be increased is 
by so regulating the conditions in ponds or parks that the natural food 
may grow in greater luxuriance. In artificial propagation the life of 
the young has been prolonged beyond the early embryonic stages by 
feeding upon certain marine algre reduced to a powder by pounding 
them in a mortar, but such successes have been purely experimental 
and are of no significance from a practical standpoint. Even if artificial 
propagation were to obtain a place in practical oyster- culture, the fry 
would doubtless be liberated before resort to artificial feeding would 
become necessary. 

* Fisheries Industries, Sec. I, pp. 723, 724, 725. 



336 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 

FATTENING, PLUMPING, FLOATING. 

As has been frequently pointed out, the so-called "fattening" of 
oysters for a short time previous to sending them to market is not a 
fattening process at all, but is a device of the trade to give to the 
oysters an illusive appearance of plumpness. It adds nothing whatever 
to the nutritive qualities of the oyster, but on the contrary injures its 
flavor and extracts certain of its nutritious ingredients. However, as 
long as the public desire such oysters the dealers can not be blamed lor 
supplying them. 

The process of plumping consists in changing oysters from denser to 
less dense water, causing an interchange of fluids through the walls of 
the animal, the denser fluids in the tissues passing slowly outward, the 
less saline water in which the animal is immersed passing more rapidly 
inward. The net result is to cause a swelling of the tissues by an 
increase in the fluid contents, in much the same manner as a dry 
sponge swells when moistened. The oysters are not usually placed in 
absolutely fresh water, which would kill them if exposed too long, 
but in fresher than that in which they have been living. The fluids 
which have passed out from the tissues carry with them salts and some 
fats, chemical experiment showing that the oyster, although larger after 
plumping, has lost 13 per cent of its original nutritious substances, 
protein, fats, carbohydrates, and mineral salts. Sufficient water will be 
taken up, however, to increase the total weight of the oyster from 12 to 
20 per cent. The same result is produced by placing the oysters in fresh 
water after they have been removed from the shell. It will be seen that 
what the oysters have gained is simply water, of no value as food. 

If the living oysters are left too long on the floats they will again 
become "lean," leaner than before, in fact, owing to the state of equi- 
librium which is finally established between, the density of the juices 
within the tissues and without. If oysters are taken from brackish 
water to that which is considerably more saline they become shrunken, 
tough, and leathery, owing to the converse process to that of plumping. 

Various forms of floats are used. One of the simplest consists of 
trays 8 feet by 16 feet by 2 feet deep, with perforated bottoms, these 
being raised from the water for filling and emptying by means of a chain 
attached to each corner and a pair of windlasses supported upon piles. 

While not harmful in itself it may be well in this connection to sound 
a word of warning. Oysters may, and no doubt sometimes do, consume 
pathogenic bacteria, or disease germs, with their food; and such germs, 
transferred to the human economy with vitality unimpaired may upon 
occasions have serious results. Care should be exercised to construct 
the floats in such places as are free from the contaminating influences 
of sewer discharge and other sources of pollution. 

In France the oysters are subjected to a true fattening process in 
inclosed ponds or claires, their flavor and appearance being much 
improved thereby. 



OYSTERS AND METHODS OF OYSTER-CULTURE. 337 

GREENING. 

Notwithstanding that almost every recent writer upon the subject 
has insisted upon the harmlessness of the green coloration which is 
frequently observed in certain portions of the oysters, there is still con- 
siderable misapprehension of the subject by consumers and oystermen 
alike. The prejudice is confined to America, in Europe such oysters 
being regarded as superior, and much trouble being taken to impart to 
them their peculiar viridity. In our waters the greening is liable to 
occur in certain localities and at irregular times, leather shallow 
waters appear to be more susceptible to the production of this effect 
than the greater depths, but it has recently appeared on the deep-water 
beds of Long Island Sound. 

When oysters become so colored the oystermen find great difficulty 
in disposing of them, owing to the popular belief that they are unfit for 
food, or even poisonous. They often have what is described as a cop- 
pery taste, and uninformed persons usually assume that the green color 
is due to the presence of copper. A number of careful investigations 
have shown that such oysters contain no copper whatever, but that the 
green color is derived from a harmless blue green substance, phyco- 
cyanin, which is found in certain of the lower plants. 

Under proper conditions these unicellular vegetable organisms mul- 
tiply in brackish or saline water with great rapidity and provide an 
important item of food to the oyster. The green matter is soluble in 
the juices of the oyster and passes into the tissues, affecting principally 
the blood corpuscles. 

An oyster usually shows the first indication of greening in the gills 
and palps, and frequently this is the only portion of the animal which is 
colored, a fact which is explained when we remember that this is the 
most highly vascular portion. When the supply -of greening food is 
abundant and long continued, the mantle, liver, and eventually the 
entire organism, with the exception of the muscle, acquire a green 
hue. Such oysters are usually, but not always, fat and well fed, the 
result of the abundant supply of nutritious food, and such a condition 
could hardly obtain were the dye a copper product, such as has been 
popularly supposed. 

The color may be removed from the oysters by transferring them for 
a short time to waters in which the green food is deficient, a fact 
which may be available in preparing for market oysters which popular 
prejudice refuses to use in the green state. 

In conclusion, it may be again insisted that the greening is not a 
disease, nor a parasite, nor a poisonous material in any sense. 

F. C. K. 1897 22 



338 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 



TRANSPORTATION AND LENGTH OF LIFE WHEN REMOVED 
FROM THE WATER. 

Under proper conditions the oyster will live for a long time after its 
removal from the water. Professor Verrill records a case in which 
marketable oysters survived for over ten weeks while hung up in the 
window of a shop, during the months of December, January, and 
February. The temperature was variable, but upon the whole rather 
cool. He says : 

The remarkable duration of the life of these oysters is undoubtedly due to two 
causes : 

1. The perfect condition of the edges of the shells, which allowed them to close 
ap very tightly. 

2. The position, suspended as they were with the front edge downward, is the 
most favorable position possible for the retention of water within the gill cavity, 
for in this position the edges of the mantle would closely pack against the inner 
edges of the shell, effectually closing any small leaks, and the retained water would 
also be in the most favorable position to moisten the gills, even after part had 
evaporated. It is also possible that when in this position the oyster instinctively 
keeps the shell tightly closed, to prevent the loss of water. 

This incident may give a hint as to the best mode of transporting oysters and 
clams long distances. Perfect shells should be selected, and they should be packed 
with the front edge downward and kept moderately cool in a crate or some such 
receptacle which will allow a free circulation of air. Under such faA r orable condi- 
tions selected oysters can doubtless be kept from eight to twelve weeks out of water. 

So far as is known, Professor Yerrill's suggestion has not been fol- 
lowed by shippers, who seem to have no difficulty in making shipments 
to distant points. 

Oysters are usually transported in barrels or sacks. To far inland 
or transcontinental points shipment is made in refrigerator cars. In 
the transportation of American oysters to Europe the same method of 
packing is followed, and they are carried in the cold-storage chambers 
of the vessels. 

Several devices for locking the oysters, so as to prevent the gaping 
of the valves and the escape of the fluids, have been pateuted, but 
they do not appear to be in extensive use at the present time. 

It is stated by some dealers that oysters which have been u plumped" 
or "fattened" stand shipment better than those which have not been 
subjected to the process. 

The oyster, of course, can not feed during the period of its depriva- 
tion from water, and to maintain its vitality it makes draft upon its 
own tissues and gradually becomes poorer m quality. As the vital 
activities are apparently reduced at such times, the waste of tissue is 
small. 



NOTES ON CLAM-CULTURE. 



Owing to the importance of several species of clams as food for man 
and as bait in the line fisheries, it is deemed desirable to append a 
few facts relating to them and to their cultnre. 

Two species are in common use upon the Atlantic coast, one of them 
also being an introduced species upon the Pacific coast. The quahog, 
hard clam or round clam (Mercenaria mercenaria), is perhaps the more 
important. It is the "clam" of the markets of New York, Philadel- 
phia, and southward, and it is also utilized to some extent in New 
England. It is a heavy-shelled form living on the muddy bottoms, 
principally below low-water mark, where it is taken by means of rakes 
or by the process of " treading out," the clammer wading about and 
feeling for the clams with his toes and then picking them up by hand 
or with a short rake. 

The long clam or mananose (Mya arenaria) is the principal species in 
the markets north of New York, and, on account of the comparative 
lightness of its shell, is often called the "soft" clam. This species was 
introduced on the Pacific coast with oysters brought from the Bast, 
and has now become widely distributed there and an important food 
product. It is found principally on sandy shores or in a mixture of sand 
and mud, between tide marks. Its long siphons permit it to burrow 
to a considerable depth, and it is dug from its burrows by means of 
spades, stout forks, or heavy hoes or rakes. 

The soft clam appears to be the only species which has been the 
object of attempted cultivation, although no doubt the quahog is 
equally favorable for the experiment. 

In Chesapeake Bay the soft-shell clam spawns from about September 
10 to October 20. The eggs are of about the same size as those of the 
oyster, and in their early development pass through practically the 
same stages. At the end of the free-swimming stage the clam is still 
very small. It settles to the bottom, but instead of becoming attached 
to shells or other firm bodies in the water it soon burrows into the bot- 
tom until it is completely hidden with the exception of the tips of the 
siphons, through which it derives its supply of «food and oxygen from 
the currents of water induced by the action of cells provided with hair- 
like processes (cilia). Upon very soft bottom the young clam, like the 
young oyster, is liable to become suffocated in the mad, but as it grows 

339 



340 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 

larger its powers of locomotion, which, though limited in degree, persist 
throughout life, enable it to extricate itself. 

Owing to its free-living habit, the methods in use for catching oyster 
spat can not be utilized for the growing of seed clams. Although so 
far as known no successful attempt has been made to obtain clam spat, 
it seems probable that a moderately soft bottom naturally devoid of 
clams could be made available by covering it witli a coating of sand of 
sufficient depth to prevent the sinking of the young during the early 
stages after it falls to the bottom. Later in life they are better able to 
care for themselves. 

In certain places the planting of seed clams has been attended with 
some success, as is shown in the following account: 

Quite an interesting feature in connection with the clam fisheries at Esses, Mass., 
was found in the shape of clam-culture. In 1888 an act was passed by the legislature 
authorizing the selectmen of the town to stake off in lots of 1 acre or less each of 
the flats along the Esses River, and let them to persons desiring to plant clams for a 
rental of $2 per acre or lot for five years and an additional fee of 50 cents. Thus 
far 37-J- acres have been taken up and seeded with clams. Small clams are dug on 
the natural beds and planted on these hitherto unproductive fiats. About 500 
bushels are required to plant an acre properly. During the first two years (1889 and 
1890) the people were slow to avail themselves of the privilege of planting for fear 
that after they had spent their time and labor they would not be able to secure pro- 
tection from trespassers. But in 1891 and 1892 lots were obtained and planted. 
Tho principal difficulty encountered has been the loss of the clams by the sand 
washing over them, the bottom in some localities being soft and shifting. In 1892 
there were 25 acres that we're quite productive, about one-third of the entire catch 
of the section being obtained from them. The catch from these lots is not definitely 
known, but is estimated at about 2,500 barrels. 

The cultivated clams possess some advantage over the natural growth from the 
fact that they are more uniform in size and are as large as the best of the natural 
clams. They bring $1.75 per barrel, while the natural clams sell for $1.50 per barrel 
This is the price received by the catchers. One acre of these clams is considered to 
be worth $1,000 if well seeded and favorably located so as not to be in danger of 
being submerged with sand. This valuation would be too high for an average, since 
all the acres are not equally well seeded and located. The clammers are generally 
impressed that the industry can be estensively and profitably developed, and their 
only fear is that they will not be able to secure lots permanently. The greater part 
of the land available for this purpose is covered by the deeds of people owning farms 
along the river, and the consent of the land-owners has to be obtained before lots 
can be taken up. It seems probable, however, that the business will continue to 
progress unless checked by complications that may arise relative to the occupancy 
of the grounds. — Report U. S. Fish Commission, 1894, pp. 139, 140. 

It was hoped that these planted clams would propagate on the new 
beds, but the expectation has not been realized, owing, no doubt, to the 
un suitableness of the bottom, a fact which would also account for the 
absence of the species in the first place. 

The growth of the soft clam is quite rapid, and Dr. Ryder has shown 
that at St. Jerome Creek, Maryland, the shells reach a length of between 
1% and l-£ inches within several months of the time of spawning. 



Report U. S. F. C. 1897. (To face page 340.) 



Plate V. 





FIG. 1, INNER FACE, AND FIG. 2, OUTER FACE OF SHELL OF TYPICAL AMERICAN OYSTER. 
From Fourth Annual Report, U. S. Geological Survey. 



% % \§& 



Report U. S. F. C. 1897. (To face page 340.) 



Plate VI. 






Fig. 1. Upper view of closed valves of Pacific oyster, Ostrea lurida. 
Fig. 2. Inner face of ventral valve of same specimen. 
Fig. 3. Outer face of ventral valve of same specimen. 



A Sfijft: 



Report U. S. F. C. 1897, (To face page 340.) 



Plate VII. 




Fig. 1. Unfertilized egg shortly 

after mixture of spawn and milt; 

spermatozoa are adhering to the 

surface. 
Fig. 3. Egg after fertilization. 
Fig. 3. Same egg 2 minutes later. 

Polar body at broad end. 
Fig. 4. Same egg 6 minutes later. 
Fig. 5. About 61 hours later. 
Fig. 6. Another egg at about the 

same stage. Mass of small cells 

growing over large cell or mac- 

romere a. 
Fig. 7. Egg 55 minutes later. Mac- 

romere almost covered by small 

cells of ectoderm. 



Fig. 8. Optical section of egg 27 
hours after impregnation, show- 
ing two large cells, derived from 
a in fig 6, covered by a layer of 
small ectodermal cells. 

Fig. 9. Egg a few hours older,show- 
ing large cells viewed from below. 

Fig. 10. An egg somewhat older 
viewed from above, showing fur 
ther subdivision of large cells as 
seen through cells of upper layer. 

Fig. 11. An older egg, now become 
flattened from above downward. 
Viewed in optical section. 

Fig. 12. Surface view of an embryo 
just beginning to swim. 

After W. K. Brooks. 



Fig. 13. Optical section of same. 

Fig. 14. Surface view of same from 
another position. 

Fig. 15. Surface view of same from 
another position. 

Fig. 16. An older embryo in same 
position as in fig 12. 

Fig. 17. A still older embryo show- 
ing spherical ciliated digestive 
cavity opening by mouth, m. 

Fig. 18. An embryo with well-de- 
veloped larval shells, older than 
fig. 1, Plate VIII. rs, right shell; 
Is, left shell; vl, velum; m, 
mouth. 



Report U. S. F. C. 1897. (To face page 340.) 



Plate VIII. 




Fig. 1. View of right side of embryo about G days old. m, mouth; v, vent; I, right lobe of liver; vl, velum. 

Fig. 2. Older larva of European oyster, Ostrea lurida. L, shell; h, hinge; rs and ri, retractor muscles of 
the velum, vl; s, stomach; i, intestine; am, larval adductor muscle; b, body cavity. Other letters as in 
the preceding. 

Fig. 3. Attached spat of Ostrea virginiana. S, shell of spat with larval shell, L, at the beak or umbo; p, 
palps; g, gills; c, diagrammatic representation of a single row of cillia extending from the mantle border to 
the mouth m; r, radiating muscle fibres of mantle; t, rudimentary tentacles of mantle border; M, perma- 
nent adductor muscle; C, cloaca; ve and cm, ventricle and auricle of the heart; y, posterior extremity of 
the gills and junction of the mantle folds. Other figures as above. Compare this figure with PI. I, fig. 1. 

Fig. 1 after "W. K. Brooks. Fig. 2 after Thomas H. Huxley. Fig. 3 after John A. Ryder. 



Report U. S. F, C. 1 897. (To face page 340.) 



Plate IX. 




SET OF OYSTERS ON RACCOON OYSTER SHELL, SHOWING CROWDING. NATURAL SIZE. 



Report U. S. F. C. 1897. (To face page 340.) 



Plate X. 




OYSTER SPAT TWO OR THREE WEEKS OLD ON INSIDE OF OYSTER SHELL. 
NATURAL SIZE. 



Report U. S. F. C. 1897. (To face page 340.) 



Plate XI. 




OYSTER SPAT ABOUT TWO MONTHS OLD, ON A STONE. NATURAL SIZE. 



Report U. S. F. C. 1897. (To face page 340.) 



Plate XII. 






FIGS. 1, 2, AND 3, OYSTERS ONE, TWO, AND THREE YEARS OLD, RESPECTIVELY. NATURAL SIZE. 
Grown on hard bottom in Long Island Sound. 



Report U S. F. C. 1897. (To face page 340 ) 



Plate XIII. 




FIGS. 1 AND 2, OYSTERS FOUR AND FIVE YEARS OLD, RESPECTIVELY. NATURAL SIZE. 
Grown on hard bottom in Long Island Sound. 



Report U. S. F. C. 1897. (To face paee 340.) 



Plate XIV. 




Fig. 1. PHOTO-MICROGRAPH OF THE DIATOM. SURIRELLA GEMMA, ENLARGED ABOUT 1,600 

DIAMETERS. 

The tip of the frustule is alone given, to indicate the character and texture of the glassy surface. 




Fig. 2. FOOD OF SOUTH CAROLINA OYSTER. A FEW TYPICAL ORGANISMS ( x 225). 
Numbers 1 to 20 are diatoms. 



1-5. Navicula (Bory). 

6. N. didyma(K.). 14. Cyclotella rotula (E.). 

7. Pinnuiaria radiosa (?) (K. S.). 15. Synedra sp. (E.). 

8. Amphora sp. (K.). 16. Diatoma sp. (De C). 

9. Pleurosigma fasciola (E. S.). 17. Cymbella sp. ( Ag.). 

10. P. littorale (SA 18. Mastogloia smithii (ThwA 

11. P. strigosum (S.). 19. Triceratium alternans (Br, 

12. Actinocyclusundulatus(K.). Bai.). 



13. Coscinodiscus radiatus (E.). 20. Biddulphia sp. (Gr.). 

21. Grain of pine pollen (Pinus 



rigida). 

22. Foraminifera (Rotalia). 

23. Zoospore (Ulva ?). 

24. Spicules. 

(After Bashford Dean.) 



Report U. S. F. C. 1 897. (To face page 340.) 



Plate XV. 




Fig. 1. Drill, Urosalpinx cinerea. 
Fig. 2. Mussel, Mytilus edulis. 



Fig. 3. Sabellaria vulgaris. 

Fig. 4. Periwinkle, Fulgur carica. 



Report U. S. F. C. 1897. (To face page 340.) 



Plate XVI 




Report U. S. F. C. 1897. (To face page 340 



Plate XVII. 




BUNCH OF OYSTERS FROM GREAT POINT CLEAR REEF. SHOWING GROWTH OF MUSSELS AND 

BARNACLES. 
From Bulletin U. S. Fish Commission, 1895. 



Report U. S. F. C. 1897. (To face page 34G.) 



Plate XVIII. 








, "> - v-.TT^r-*^ 

ml lil 




Hit- - - ' 'Sill 




Fig. 1. "Quarter-decker," Crepidula fomicata. 
Fig. 2. "Quarter-decker," Crepidula plana. 
Fig. 3. "Quarter-decker," Crepidula convexa. 
Fig. 4. Jingle, Anomia glabra, profile view. 
Fig. 5. The same, lower side. 
Fig. 6. Scallop, Pecten irradians. 
Fig. 7. Oyster attached to pebble. 



Plate 35. 




R.port U. S. F. C, 1897, (To face psgo 340,) 




VIEW OF BATTERY FOR HATCHING WHITEFISH. 









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